R/DataFrame.R
In vkapartzianis/SparkR: R Frontend for Apache Spark
#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# DataFrame.R - SparkDataFrame class and methods implemented in S4 OO classes
#' @include generics.R jobj.R schema.R RDD.R pairRDD.R column.R group.R
NULL
setOldClass("jobj")
setOldClass("structType")
#' S4 class that represents a SparkDataFrame
#'
#' SparkDataFrames can be created using functions like \link{createDataFrame},
#' \link{read.json}, \link{table} etc.
#'
#' @family SparkDataFrame functions
#' @rdname SparkDataFrame
#' @docType class
#'
#' @slot env An R environment that stores bookkeeping states of the SparkDataFrame
#' @slot sdf A Java object reference to the backing Scala DataFrame
#' @seealso \link{createDataFrame}, \link{read.json}, \link{table}
#' @seealso \url{https://spark.apache.org/docs/latest/sparkr.html#sparkr-dataframes}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df <- createDataFrame(faithful)
#'}
#' @note SparkDataFrame since 2.0.0
setClass("SparkDataFrame",
slots = list(env = "environment",
sdf = "jobj"))
setMethod("initialize", "SparkDataFrame", function(.Object, sdf, isCached) {
.Object@env <- new.env()
.Object@env$isCached <- isCached
.Object@sdf <- sdf
.Object
})
#' Set options/mode and then return the write object
#' @noRd
setWriteOptions <- function(write, path = NULL, mode = "error", ...) {
options <- varargsToStrEnv(...)
if (!is.null(path)) {
options[["path"]] <- path
}
write <- setWriteMode(write, mode)
write <- callJMethod(write, "options", options)
write
}
#' Set mode and then return the write object
#' @noRd
setWriteMode <- function(write, mode) {
if (!is.character(mode)) {
stop("mode should be character or omitted. It is 'error' by default.")
}
write <- handledCallJMethod(write, "mode", mode)
write
}
#' @export
#' @param sdf A Java object reference to the backing Scala DataFrame
#' @param isCached TRUE if the SparkDataFrame is cached
#' @noRd
dataFrame <- function(sdf, isCached = FALSE) {
new("SparkDataFrame", sdf, isCached)
}
############################ SparkDataFrame Methods ##############################################
#' Print Schema of a SparkDataFrame
#'
#' Prints out the schema in tree format
#'
#' @param x A SparkDataFrame
#'
#' @family SparkDataFrame functions
#' @rdname printSchema
#' @name printSchema
#' @aliases printSchema,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' printSchema(df)
#'}
#' @note printSchema since 1.4.0
setMethod("printSchema",
signature(x = "SparkDataFrame"),
function(x) {
schemaString <- callJMethod(schema(x)$jobj, "treeString")
cat(schemaString)
})
#' Get schema object
#'
#' Returns the schema of this SparkDataFrame as a structType object.
#'
#' @param x A SparkDataFrame
#'
#' @family SparkDataFrame functions
#' @rdname schema
#' @name schema
#' @aliases schema,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' dfSchema <- schema(df)
#'}
#' @note schema since 1.4.0
setMethod("schema",
signature(x = "SparkDataFrame"),
function(x) {
structType(callJMethod(x@sdf, "schema"))
})
#' Explain
#'
#' Print the logical and physical Catalyst plans to the console for debugging.
#'
#' @family SparkDataFrame functions
#' @aliases explain,SparkDataFrame-method
#' @rdname explain
#' @name explain
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' explain(df, TRUE)
#'}
#' @note explain since 1.4.0
setMethod("explain",
signature(x = "SparkDataFrame"),
function(x, extended = FALSE) {
queryExec <- callJMethod(x@sdf, "queryExecution")
if (extended) {
cat(callJMethod(queryExec, "toString"))
} else {
execPlan <- callJMethod(queryExec, "executedPlan")
cat(callJMethod(execPlan, "toString"))
}
})
#' isLocal
#'
#' Returns True if the \code{collect} and \code{take} methods can be run locally
#' (without any Spark executors).
#'
#' @param x A SparkDataFrame
#'
#' @family SparkDataFrame functions
#' @rdname isLocal
#' @name isLocal
#' @aliases isLocal,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' isLocal(df)
#'}
#' @note isLocal since 1.4.0
setMethod("isLocal",
signature(x = "SparkDataFrame"),
function(x) {
callJMethod(x@sdf, "isLocal")
})
#' showDF
#'
#' Print the first numRows rows of a SparkDataFrame
#'
#' @param x a SparkDataFrame.
#' @param numRows the number of rows to print. Defaults to 20.
#' @param truncate whether truncate long strings. If \code{TRUE}, strings more than
#' 20 characters will be truncated. However, if set greater than zero,
#' truncates strings longer than \code{truncate} characters and all cells
#' will be aligned right.
#' @param vertical whether print output rows vertically (one line per column value).
#' @param ... further arguments to be passed to or from other methods.
#' @family SparkDataFrame functions
#' @aliases showDF,SparkDataFrame-method
#' @rdname showDF
#' @name showDF
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' showDF(df)
#'}
#' @note showDF since 1.4.0
setMethod("showDF",
signature(x = "SparkDataFrame"),
function(x, numRows = 20, truncate = TRUE, vertical = FALSE) {
if (is.logical(truncate) && truncate) {
s <- callJMethod(x@sdf, "showString", numToInt(numRows), numToInt(20), vertical)
} else {
truncate2 <- as.numeric(truncate)
s <- callJMethod(x@sdf, "showString", numToInt(numRows), numToInt(truncate2),
vertical)
}
cat(s)
})
#' show
#'
#' Print class and type information of a Spark object.
#'
#' @param object a Spark object. Can be a SparkDataFrame, Column, GroupedData, WindowSpec.
#'
#' @family SparkDataFrame functions
#' @rdname show
#' @aliases show,SparkDataFrame-method
#' @name show
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' show(df)
#'}
#' @note show(SparkDataFrame) since 1.4.0
setMethod("show", "SparkDataFrame",
function(object) {
cols <- lapply(dtypes(object), function(l) {
paste(l, collapse = ":")
})
s <- paste(cols, collapse = ", ")
cat(paste(class(object), "[", s, "]\n", sep = ""))
})
#' DataTypes
#'
#' Return all column names and their data types as a list
#'
#' @param x A SparkDataFrame
#'
#' @family SparkDataFrame functions
#' @rdname dtypes
#' @name dtypes
#' @aliases dtypes,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' dtypes(df)
#'}
#' @note dtypes since 1.4.0
setMethod("dtypes",
signature(x = "SparkDataFrame"),
function(x) {
lapply(schema(x)$fields(), function(f) {
c(f$name(), f$dataType.simpleString())
})
})
#' Column Names of SparkDataFrame
#'
#' Return a vector of column names.
#'
#' @param x a SparkDataFrame.
#'
#' @family SparkDataFrame functions
#' @rdname columns
#' @name columns
#' @aliases columns,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' columns(df)
#' colnames(df)
#'}
#' @note columns since 1.4.0
setMethod("columns",
signature(x = "SparkDataFrame"),
function(x) {
sapply(schema(x)$fields(), function(f) {
f$name()
})
})
#' @rdname columns
#' @name names
#' @aliases names,SparkDataFrame-method
#' @note names since 1.5.0
setMethod("names",
signature(x = "SparkDataFrame"),
function(x) {
columns(x)
})
#' @rdname columns
#' @aliases names<-,SparkDataFrame-method
#' @name names<-
#' @note names<- since 1.5.0
setMethod("names<-",
signature(x = "SparkDataFrame"),
function(x, value) {
colnames(x) <- value
x
})
#' @rdname columns
#' @aliases colnames,SparkDataFrame-method
#' @name colnames
#' @note colnames since 1.6.0
setMethod("colnames",
signature(x = "SparkDataFrame"),
function(x) {
columns(x)
})
#' @param value a character vector. Must have the same length as the number
#' of columns to be renamed.
#' @rdname columns
#' @aliases colnames<-,SparkDataFrame-method
#' @name colnames<-
#' @note colnames<- since 1.6.0
setMethod("colnames<-",
signature(x = "SparkDataFrame"),
function(x, value) {
# Check parameter integrity
if (class(value) != "character") {
stop("Invalid column names.")
}
if (length(value) != ncol(x)) {
stop(
"Column names must have the same length as the number of columns in the dataset.")
}
if (any(is.na(value))) {
stop("Column names cannot be NA.")
}
# Check if the column names have . in it
if (any(regexec(".", value, fixed = TRUE)[[1]][1] != -1)) {
stop("Column names cannot contain the '.' symbol.")
}
sdf <- callJMethod(x@sdf, "toDF", as.list(value))
dataFrame(sdf)
})
#' coltypes
#'
#' Get column types of a SparkDataFrame
#'
#' @param x A SparkDataFrame
#' @return value A character vector with the column types of the given SparkDataFrame
#' @rdname coltypes
#' @aliases coltypes,SparkDataFrame-method
#' @name coltypes
#' @family SparkDataFrame functions
#' @export
#' @examples
#'\dontrun{
#' irisDF <- createDataFrame(iris)
#' coltypes(irisDF) # get column types
#'}
#' @note coltypes since 1.6.0
setMethod("coltypes",
signature(x = "SparkDataFrame"),
function(x) {
# Get the data types of the SparkDataFrame by invoking dtypes() function
types <- sapply(dtypes(x), function(x) {x[[2]]})
# Map Spark data types into R's data types using DATA_TYPES environment
rTypes <- sapply(types, USE.NAMES = F, FUN = function(x) {
# Check for primitive types
type <- PRIMITIVE_TYPES[[x]]
if (is.null(type)) {
# Check for complex types
for (t in names(COMPLEX_TYPES)) {
if (substring(x, 1, nchar(t)) == t) {
type <- COMPLEX_TYPES[[t]]
break
}
}
if (is.null(type)) {
specialtype <- specialtypeshandle(x)
if (is.null(specialtype)) {
stop(paste("Unsupported data type: ", x))
}
type <- PRIMITIVE_TYPES[[specialtype]]
}
}
type[[1]]
})
# Find which types don't have mapping to R
naIndices <- which(is.na(rTypes))
# Assign the original scala data types to the unmatched ones
rTypes[naIndices] <- types[naIndices]
rTypes
})
#' coltypes
#'
#' Set the column types of a SparkDataFrame.
#'
#' @param value A character vector with the target column types for the given
#' SparkDataFrame. Column types can be one of integer, numeric/double, character, logical, or NA
#' to keep that column as-is.
#' @rdname coltypes
#' @name coltypes<-
#' @aliases coltypes<-,SparkDataFrame,character-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' coltypes(df) <- c("character", "integer") # set column types
#' coltypes(df) <- c(NA, "numeric") # set column types
#'}
#' @note coltypes<- since 1.6.0
setMethod("coltypes<-",
signature(x = "SparkDataFrame", value = "character"),
function(x, value) {
cols <- columns(x)
ncols <- length(cols)
if (length(value) == 0) {
stop("Cannot set types of an empty SparkDataFrame with no Column")
}
if (length(value) != ncols) {
stop("Length of type vector should match the number of columns for SparkDataFrame")
}
newCols <- lapply(seq_len(ncols), function(i) {
col <- getColumn(x, cols[i])
if (!is.na(value[i])) {
stype <- rToSQLTypes[[value[i]]]
if (is.null(stype)) {
stop("Only atomic type is supported for column types")
}
cast(col, stype)
} else {
col
}
})
nx <- select(x, newCols)
dataFrame(nx@sdf)
})
#' Creates a temporary view using the given name.
#'
#' Creates a new temporary view using a SparkDataFrame in the Spark Session. If a
#' temporary view with the same name already exists, replaces it.
#'
#' @param x A SparkDataFrame
#' @param viewName A character vector containing the name of the table
#'
#' @family SparkDataFrame functions
#' @rdname createOrReplaceTempView
#' @name createOrReplaceTempView
#' @aliases createOrReplaceTempView,SparkDataFrame,character-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' createOrReplaceTempView(df, "json_df")
#' new_df <- sql("SELECT * FROM json_df")
#'}
#' @note createOrReplaceTempView since 2.0.0
setMethod("createOrReplaceTempView",
signature(x = "SparkDataFrame", viewName = "character"),
function(x, viewName) {
invisible(callJMethod(x@sdf, "createOrReplaceTempView", viewName))
})
#' (Deprecated) Register Temporary Table
#'
#' Registers a SparkDataFrame as a Temporary Table in the SparkSession
#' @param x A SparkDataFrame
#' @param tableName A character vector containing the name of the table
#'
#' @family SparkDataFrame functions
#' @seealso \link{createOrReplaceTempView}
#' @rdname registerTempTable-deprecated
#' @name registerTempTable
#' @aliases registerTempTable,SparkDataFrame,character-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' registerTempTable(df, "json_df")
#' new_df <- sql("SELECT * FROM json_df")
#'}
#' @note registerTempTable since 1.4.0
setMethod("registerTempTable",
signature(x = "SparkDataFrame", tableName = "character"),
function(x, tableName) {
.Deprecated("createOrReplaceTempView")
invisible(callJMethod(x@sdf, "createOrReplaceTempView", tableName))
})
#' insertInto
#'
#' Insert the contents of a SparkDataFrame into a table registered in the current SparkSession.
#'
#' @param x a SparkDataFrame.
#' @param tableName a character vector containing the name of the table.
#' @param overwrite a logical argument indicating whether or not to overwrite.
#' @param ... further arguments to be passed to or from other methods.
#' the existing rows in the table.
#'
#' @family SparkDataFrame functions
#' @rdname insertInto
#' @name insertInto
#' @aliases insertInto,SparkDataFrame,character-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df <- read.df(path, "parquet")
#' df2 <- read.df(path2, "parquet")
#' saveAsTable(df, "table1")
#' insertInto(df2, "table1", overwrite = TRUE)
#'}
#' @note insertInto since 1.4.0
setMethod("insertInto",
signature(x = "SparkDataFrame", tableName = "character"),
function(x, tableName, overwrite = FALSE) {
write <- callJMethod(x@sdf, "write")
write <- setWriteMode(write, ifelse(overwrite, "overwrite", "append"))
invisible(callJMethod(write, "insertInto", tableName))
})
#' Cache
#'
#' Persist with the default storage level (MEMORY_ONLY).
#'
#' @param x A SparkDataFrame
#'
#' @family SparkDataFrame functions
#' @aliases cache,SparkDataFrame-method
#' @rdname cache
#' @name cache
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' cache(df)
#'}
#' @note cache since 1.4.0
setMethod("cache",
signature(x = "SparkDataFrame"),
function(x) {
cached <- callJMethod(x@sdf, "cache")
x@env$isCached <- TRUE
x
})
#' Persist
#'
#' Persist this SparkDataFrame with the specified storage level. For details of the
#' supported storage levels, refer to
#' \url{http://spark.apache.org/docs/latest/rdd-programming-guide.html#rdd-persistence}.
#'
#' @param x the SparkDataFrame to persist.
#' @param newLevel storage level chosen for the persistance. See available options in
#' the description.
#'
#' @family SparkDataFrame functions
#' @rdname persist
#' @name persist
#' @aliases persist,SparkDataFrame,character-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' persist(df, "MEMORY_AND_DISK")
#'}
#' @note persist since 1.4.0
setMethod("persist",
signature(x = "SparkDataFrame", newLevel = "character"),
function(x, newLevel) {
callJMethod(x@sdf, "persist", getStorageLevel(newLevel))
x@env$isCached <- TRUE
x
})
#' Unpersist
#'
#' Mark this SparkDataFrame as non-persistent, and remove all blocks for it from memory and
#' disk.
#'
#' @param x the SparkDataFrame to unpersist.
#' @param blocking whether to block until all blocks are deleted.
#' @param ... further arguments to be passed to or from other methods.
#'
#' @family SparkDataFrame functions
#' @rdname unpersist
#' @aliases unpersist,SparkDataFrame-method
#' @name unpersist
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' persist(df, "MEMORY_AND_DISK")
#' unpersist(df)
#'}
#' @note unpersist since 1.4.0
setMethod("unpersist",
signature(x = "SparkDataFrame"),
function(x, blocking = TRUE) {
callJMethod(x@sdf, "unpersist", blocking)
x@env$isCached <- FALSE
x
})
#' StorageLevel
#'
#' Get storagelevel of this SparkDataFrame.
#'
#' @param x the SparkDataFrame to get the storageLevel.
#'
#' @family SparkDataFrame functions
#' @rdname storageLevel
#' @aliases storageLevel,SparkDataFrame-method
#' @name storageLevel
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' persist(df, "MEMORY_AND_DISK")
#' storageLevel(df)
#'}
#' @note storageLevel since 2.1.0
setMethod("storageLevel",
signature(x = "SparkDataFrame"),
function(x) {
storageLevelToString(callJMethod(x@sdf, "storageLevel"))
})
#' Coalesce
#'
#' Returns a new SparkDataFrame that has exactly \code{numPartitions} partitions.
#' This operation results in a narrow dependency, e.g. if you go from 1000 partitions to 100
#' partitions, there will not be a shuffle, instead each of the 100 new partitions will claim 10 of
#' the current partitions. If a larger number of partitions is requested, it will stay at the
#' current number of partitions.
#'
#' However, if you're doing a drastic coalesce on a SparkDataFrame, e.g. to numPartitions = 1,
#' this may result in your computation taking place on fewer nodes than
#' you like (e.g. one node in the case of numPartitions = 1). To avoid this,
#' call \code{repartition}. This will add a shuffle step, but means the
#' current upstream partitions will be executed in parallel (per whatever
#' the current partitioning is).
#'
#' @param numPartitions the number of partitions to use.
#'
#' @family SparkDataFrame functions
#' @rdname coalesce
#' @name coalesce
#' @aliases coalesce,SparkDataFrame-method
#' @seealso \link{repartition}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' newDF <- coalesce(df, 1L)
#'}
#' @note coalesce(SparkDataFrame) since 2.1.1
setMethod("coalesce",
signature(x = "SparkDataFrame"),
function(x, numPartitions) {
stopifnot(is.numeric(numPartitions))
sdf <- callJMethod(x@sdf, "coalesce", numToInt(numPartitions))
dataFrame(sdf)
})
#' Repartition
#'
#' The following options for repartition are possible:
#' \itemize{
#' \item{1.} {Return a new SparkDataFrame that has exactly \code{numPartitions}.}
#' \item{2.} {Return a new SparkDataFrame hash partitioned by
#' the given columns into \code{numPartitions}.}
#' \item{3.} {Return a new SparkDataFrame hash partitioned by the given column(s),
#' using \code{spark.sql.shuffle.partitions} as number of partitions.}
#'}
#' @param x a SparkDataFrame.
#' @param numPartitions the number of partitions to use.
#' @param col the column by which the partitioning will be performed.
#' @param ... additional column(s) to be used in the partitioning.
#'
#' @family SparkDataFrame functions
#' @rdname repartition
#' @name repartition
#' @aliases repartition,SparkDataFrame-method
#' @seealso \link{coalesce}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' newDF <- repartition(df, 2L)
#' newDF <- repartition(df, numPartitions = 2L)
#' newDF <- repartition(df, col = df$"col1", df$"col2")
#' newDF <- repartition(df, 3L, col = df$"col1", df$"col2")
#'}
#' @note repartition since 1.4.0
setMethod("repartition",
signature(x = "SparkDataFrame"),
function(x, numPartitions = NULL, col = NULL, ...) {
if (!is.null(numPartitions) && is.numeric(numPartitions)) {
# number of partitions and columns both are specified
if (!is.null(col) && class(col) == "Column") {
cols <- list(col, ...)
jcol <- lapply(cols, function(c) { c@jc })
sdf <- callJMethod(x@sdf, "repartition", numToInt(numPartitions), jcol)
} else {
# only number of partitions is specified
sdf <- callJMethod(x@sdf, "repartition", numToInt(numPartitions))
}
} else if (!is.null(col) && class(col) == "Column") {
# only columns are specified
cols <- list(col, ...)
jcol <- lapply(cols, function(c) { c@jc })
sdf <- callJMethod(x@sdf, "repartition", jcol)
} else {
stop("Please, specify the number of partitions and/or a column(s)")
}
dataFrame(sdf)
})
#' toJSON
#'
#' Converts a SparkDataFrame into a SparkDataFrame of JSON string.
#'
#' Each row is turned into a JSON document with columns as different fields.
#' The returned SparkDataFrame has a single character column with the name \code{value}
#'
#' @param x a SparkDataFrame
#' @return a SparkDataFrame
#' @family SparkDataFrame functions
#' @rdname toJSON
#' @name toJSON
#' @aliases toJSON,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.parquet"
#' df <- read.parquet(path)
#' df_json <- toJSON(df)
#'}
#' @note toJSON since 2.2.0
setMethod("toJSON",
signature(x = "SparkDataFrame"),
function(x) {
jsonDS <- callJMethod(x@sdf, "toJSON")
df <- callJMethod(jsonDS, "toDF")
dataFrame(df)
})
#' Save the contents of SparkDataFrame as a JSON file
#'
#' Save the contents of a SparkDataFrame as a JSON file (\href{http://jsonlines.org/}{
#' JSON Lines text format or newline-delimited JSON}). Files written out
#' with this method can be read back in as a SparkDataFrame using read.json().
#'
#' @param x A SparkDataFrame
#' @param path The directory where the file is saved
#' @param mode one of 'append', 'overwrite', 'error', 'errorifexists', 'ignore'
#' save mode (it is 'error' by default)
#' @param ... additional argument(s) passed to the method.
#'
#' @family SparkDataFrame functions
#' @rdname write.json
#' @name write.json
#' @aliases write.json,SparkDataFrame,character-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' write.json(df, "/tmp/sparkr-tmp/")
#'}
#' @note write.json since 1.6.0
setMethod("write.json",
signature(x = "SparkDataFrame", path = "character"),
function(x, path, mode = "error", ...) {
write <- callJMethod(x@sdf, "write")
write <- setWriteOptions(write, mode = mode, ...)
invisible(handledCallJMethod(write, "json", path))
})
#' Save the contents of SparkDataFrame as an ORC file, preserving the schema.
#'
#' Save the contents of a SparkDataFrame as an ORC file, preserving the schema. Files written out
#' with this method can be read back in as a SparkDataFrame using read.orc().
#'
#' @param x A SparkDataFrame
#' @param path The directory where the file is saved
#' @param mode one of 'append', 'overwrite', 'error', 'errorifexists', 'ignore'
#' save mode (it is 'error' by default)
#' @param ... additional argument(s) passed to the method.
#'
#' @family SparkDataFrame functions
#' @aliases write.orc,SparkDataFrame,character-method
#' @rdname write.orc
#' @name write.orc
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' write.orc(df, "/tmp/sparkr-tmp1/")
#' }
#' @note write.orc since 2.0.0
setMethod("write.orc",
signature(x = "SparkDataFrame", path = "character"),
function(x, path, mode = "error", ...) {
write <- callJMethod(x@sdf, "write")
write <- setWriteOptions(write, mode = mode, ...)
invisible(handledCallJMethod(write, "orc", path))
})
#' Save the contents of SparkDataFrame as a Parquet file, preserving the schema.
#'
#' Save the contents of a SparkDataFrame as a Parquet file, preserving the schema. Files written out
#' with this method can be read back in as a SparkDataFrame using read.parquet().
#'
#' @param x A SparkDataFrame
#' @param path The directory where the file is saved
#' @param mode one of 'append', 'overwrite', 'error', 'errorifexists', 'ignore'
#' save mode (it is 'error' by default)
#' @param ... additional argument(s) passed to the method.
#'
#' @family SparkDataFrame functions
#' @rdname write.parquet
#' @name write.parquet
#' @aliases write.parquet,SparkDataFrame,character-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' write.parquet(df, "/tmp/sparkr-tmp1/")
#' saveAsParquetFile(df, "/tmp/sparkr-tmp2/")
#'}
#' @note write.parquet since 1.6.0
setMethod("write.parquet",
signature(x = "SparkDataFrame", path = "character"),
function(x, path, mode = "error", ...) {
write <- callJMethod(x@sdf, "write")
write <- setWriteOptions(write, mode = mode, ...)
invisible(handledCallJMethod(write, "parquet", path))
})
#' @rdname write.parquet
#' @name saveAsParquetFile
#' @aliases saveAsParquetFile,SparkDataFrame,character-method
#' @export
#' @note saveAsParquetFile since 1.4.0
setMethod("saveAsParquetFile",
signature(x = "SparkDataFrame", path = "character"),
function(x, path) {
.Deprecated("write.parquet")
write.parquet(x, path)
})
#' Save the content of SparkDataFrame in a text file at the specified path.
#'
#' Save the content of the SparkDataFrame in a text file at the specified path.
#' The SparkDataFrame must have only one column of string type with the name "value".
#' Each row becomes a new line in the output file.
#'
#' @param x A SparkDataFrame
#' @param path The directory where the file is saved
#' @param mode one of 'append', 'overwrite', 'error', 'errorifexists', 'ignore'
#' save mode (it is 'error' by default)
#' @param ... additional argument(s) passed to the method.
#'
#' @family SparkDataFrame functions
#' @aliases write.text,SparkDataFrame,character-method
#' @rdname write.text
#' @name write.text
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.txt"
#' df <- read.text(path)
#' write.text(df, "/tmp/sparkr-tmp/")
#'}
#' @note write.text since 2.0.0
setMethod("write.text",
signature(x = "SparkDataFrame", path = "character"),
function(x, path, mode = "error", ...) {
write <- callJMethod(x@sdf, "write")
write <- setWriteOptions(write, mode = mode, ...)
invisible(handledCallJMethod(write, "text", path))
})
#' Distinct
#'
#' Return a new SparkDataFrame containing the distinct rows in this SparkDataFrame.
#'
#' @param x A SparkDataFrame
#'
#' @family SparkDataFrame functions
#' @aliases distinct,SparkDataFrame-method
#' @rdname distinct
#' @name distinct
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' distinctDF <- distinct(df)
#'}
#' @note distinct since 1.4.0
setMethod("distinct",
signature(x = "SparkDataFrame"),
function(x) {
sdf <- callJMethod(x@sdf, "distinct")
dataFrame(sdf)
})
#' @rdname distinct
#' @name unique
#' @aliases unique,SparkDataFrame-method
#' @note unique since 1.5.0
setMethod("unique",
signature(x = "SparkDataFrame"),
function(x) {
distinct(x)
})
#' Sample
#'
#' Return a sampled subset of this SparkDataFrame using a random seed.
#' Note: this is not guaranteed to provide exactly the fraction specified
#' of the total count of of the given SparkDataFrame.
#'
#' @param x A SparkDataFrame
#' @param withReplacement Sampling with replacement or not
#' @param fraction The (rough) sample target fraction
#' @param seed Randomness seed value. Default is a random seed.
#'
#' @family SparkDataFrame functions
#' @aliases sample,SparkDataFrame-method
#' @rdname sample
#' @name sample
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' collect(sample(df, fraction = 0.5))
#' collect(sample(df, FALSE, 0.5))
#' collect(sample(df, TRUE, 0.5, seed = 3))
#'}
#' @note sample since 1.4.0
setMethod("sample",
signature(x = "SparkDataFrame"),
function(x, withReplacement = FALSE, fraction, seed) {
if (!is.numeric(fraction)) {
stop(paste("fraction must be numeric; however, got", class(fraction)))
}
if (!is.logical(withReplacement)) {
stop(paste("withReplacement must be logical; however, got", class(withReplacement)))
}
if (!missing(seed)) {
if (is.null(seed)) {
stop("seed must not be NULL or NA; however, got NULL")
}
if (is.na(seed)) {
stop("seed must not be NULL or NA; however, got NA")
}
# TODO : Figure out how to send integer as java.lang.Long to JVM so
# we can send seed as an argument through callJMethod
sdf <- handledCallJMethod(x@sdf, "sample", as.logical(withReplacement),
as.numeric(fraction), as.integer(seed))
} else {
sdf <- handledCallJMethod(x@sdf, "sample",
as.logical(withReplacement), as.numeric(fraction))
}
dataFrame(sdf)
})
#' @rdname sample
#' @aliases sample_frac,SparkDataFrame-method
#' @name sample_frac
#' @note sample_frac since 1.4.0
setMethod("sample_frac",
signature(x = "SparkDataFrame"),
function(x, withReplacement = FALSE, fraction, seed) {
sample(x, withReplacement, fraction, seed)
})
#' Returns the number of rows in a SparkDataFrame
#'
#' @param x a SparkDataFrame.
#' @family SparkDataFrame functions
#' @rdname nrow
#' @name nrow
#' @aliases count,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' count(df)
#' }
#' @note count since 1.4.0
setMethod("count",
signature(x = "SparkDataFrame"),
function(x) {
callJMethod(x@sdf, "count")
})
#' @name nrow
#' @rdname nrow
#' @aliases nrow,SparkDataFrame-method
#' @note nrow since 1.5.0
setMethod("nrow",
signature(x = "SparkDataFrame"),
function(x) {
count(x)
})
#' Returns the number of columns in a SparkDataFrame
#'
#' @param x a SparkDataFrame
#'
#' @family SparkDataFrame functions
#' @rdname ncol
#' @name ncol
#' @aliases ncol,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' ncol(df)
#' }
#' @note ncol since 1.5.0
setMethod("ncol",
signature(x = "SparkDataFrame"),
function(x) {
length(columns(x))
})
#' Returns the dimensions of SparkDataFrame
#'
#' Returns the dimensions (number of rows and columns) of a SparkDataFrame
#' @param x a SparkDataFrame
#'
#' @family SparkDataFrame functions
#' @rdname dim
#' @aliases dim,SparkDataFrame-method
#' @name dim
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' dim(df)
#' }
#' @note dim since 1.5.0
setMethod("dim",
signature(x = "SparkDataFrame"),
function(x) {
c(count(x), ncol(x))
})
#' Collects all the elements of a SparkDataFrame and coerces them into an R data.frame.
#'
#' @param x a SparkDataFrame.
#' @param stringsAsFactors (Optional) a logical indicating whether or not string columns
#' should be converted to factors. FALSE by default.
#' @param ... further arguments to be passed to or from other methods.
#'
#' @family SparkDataFrame functions
#' @rdname collect
#' @aliases collect,SparkDataFrame-method
#' @name collect
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' collected <- collect(df)
#' class(collected)
#' firstName <- names(collected)[1]
#' }
#' @note collect since 1.4.0
setMethod("collect",
signature(x = "SparkDataFrame"),
function(x, stringsAsFactors = FALSE) {
dtypes <- dtypes(x)
ncol <- length(dtypes)
if (ncol <= 0) {
# empty data.frame with 0 columns and 0 rows
data.frame()
} else {
# listCols is a list of columns
listCols <- callJStatic("org.apache.spark.sql.api.r.SQLUtils", "dfToCols", x@sdf)
stopifnot(length(listCols) == ncol)
# An empty data.frame with 0 columns and number of rows as collected
nrow <- length(listCols[[1]])
if (nrow <= 0) {
df <- data.frame()
} else {
df <- data.frame(row.names = 1 : nrow)
}
# Append columns one by one
for (colIndex in 1 : ncol) {
# Note: appending a column of list type into a data.frame so that
# data of complex type can be held. But getting a cell from a column
# of list type returns a list instead of a vector. So for columns of
# non-complex type, append them as vector.
#
# For columns of complex type, be careful to access them.
# Get a column of complex type returns a list.
# Get a cell from a column of complex type returns a list instead of a vector.
col <- listCols[[colIndex]]
if (length(col) <= 0) {
df[[colIndex]] <- col
} else {
colType <- dtypes[[colIndex]][[2]]
if (is.null(PRIMITIVE_TYPES[[colType]])) {
specialtype <- specialtypeshandle(colType)
if (!is.null(specialtype)) {
colType <- specialtype
}
}
# Note that "binary" columns behave like complex types.
if (!is.null(PRIMITIVE_TYPES[[colType]]) && colType != "binary") {
vec <- do.call(c, col)
stopifnot(class(vec) != "list")
class(vec) <- PRIMITIVE_TYPES[[colType]]
if (is.character(vec) && stringsAsFactors) {
vec <- as.factor(vec)
}
df[[colIndex]] <- vec
} else {
df[[colIndex]] <- col
}
}
}
names(df) <- names(x)
df
}
})
#' Limit
#'
#' Limit the resulting SparkDataFrame to the number of rows specified.
#'
#' @param x A SparkDataFrame
#' @param num The number of rows to return
#' @return A new SparkDataFrame containing the number of rows specified.
#'
#' @family SparkDataFrame functions
#' @rdname limit
#' @name limit
#' @aliases limit,SparkDataFrame,numeric-method
#' @export
#' @examples
#' \dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' limitedDF <- limit(df, 10)
#' }
#' @note limit since 1.4.0
setMethod("limit",
signature(x = "SparkDataFrame", num = "numeric"),
function(x, num) {
res <- callJMethod(x@sdf, "limit", as.integer(num))
dataFrame(res)
})
#' Take the first NUM rows of a SparkDataFrame and return the results as a R data.frame
#'
#' @param x a SparkDataFrame.
#' @param num number of rows to take.
#' @family SparkDataFrame functions
#' @rdname take
#' @name take
#' @aliases take,SparkDataFrame,numeric-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' take(df, 2)
#' }
#' @note take since 1.4.0
setMethod("take",
signature(x = "SparkDataFrame", num = "numeric"),
function(x, num) {
limited <- limit(x, num)
collect(limited)
})
#' Head
#'
#' Return the first \code{num} rows of a SparkDataFrame as a R data.frame. If \code{num} is not
#' specified, then head() returns the first 6 rows as with R data.frame.
#'
#' @param x a SparkDataFrame.
#' @param num the number of rows to return. Default is 6.
#' @return A data.frame.
#'
#' @family SparkDataFrame functions
#' @aliases head,SparkDataFrame-method
#' @rdname head
#' @name head
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' head(df)
#' }
#' @note head since 1.4.0
setMethod("head",
signature(x = "SparkDataFrame"),
function(x, num = 6L) {
# Default num is 6L in keeping with R's data.frame convention
take(x, num)
})
#' Return the first row of a SparkDataFrame
#'
#' @param x a SparkDataFrame or a column used in aggregation function.
#' @param ... further arguments to be passed to or from other methods.
#'
#' @family SparkDataFrame functions
#' @aliases first,SparkDataFrame-method
#' @rdname first
#' @name first
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' first(df)
#' }
#' @note first(SparkDataFrame) since 1.4.0
setMethod("first",
signature(x = "SparkDataFrame"),
function(x) {
take(x, 1)
})
#' toRDD
#'
#' Converts a SparkDataFrame to an RDD while preserving column names.
#'
#' @param x A SparkDataFrame
#'
#' @noRd
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' rdd <- toRDD(df)
#'}
setMethod("toRDD",
signature(x = "SparkDataFrame"),
function(x) {
jrdd <- callJStatic("org.apache.spark.sql.api.r.SQLUtils", "dfToRowRDD", x@sdf)
colNames <- callJMethod(x@sdf, "columns")
rdd <- RDD(jrdd, serializedMode = "row")
lapply(rdd, function(row) {
names(row) <- colNames
row
})
})
#' GroupBy
#'
#' Groups the SparkDataFrame using the specified columns, so we can run aggregation on them.
#'
#' @param x a SparkDataFrame.
#' @param ... character name(s) or Column(s) to group on.
#' @return A GroupedData.
#' @family SparkDataFrame functions
#' @aliases groupBy,SparkDataFrame-method
#' @rdname groupBy
#' @name groupBy
#' @export
#' @examples
#' \dontrun{
#' # Compute the average for all numeric columns grouped by department.
#' avg(groupBy(df, "department"))
#'
#' # Compute the max age and average salary, grouped by department and gender.
#' agg(groupBy(df, "department", "gender"), salary="avg", "age" -> "max")
#' }
#' @note groupBy since 1.4.0
#' @seealso \link{agg}, \link{cube}, \link{rollup}
setMethod("groupBy",
signature(x = "SparkDataFrame"),
function(x, ...) {
cols <- list(...)
if (length(cols) >= 1 && class(cols[[1]]) == "character") {
sgd <- callJMethod(x@sdf, "groupBy", cols[[1]], cols[-1])
} else {
jcol <- lapply(cols, function(c) { c@jc })
sgd <- callJMethod(x@sdf, "groupBy", jcol)
}
groupedData(sgd)
})
#' @rdname groupBy
#' @name group_by
#' @aliases group_by,SparkDataFrame-method
#' @note group_by since 1.4.0
setMethod("group_by",
signature(x = "SparkDataFrame"),
function(x, ...) {
groupBy(x, ...)
})
#' Summarize data across columns
#'
#' Compute aggregates by specifying a list of columns
#'
#' @family SparkDataFrame functions
#' @aliases agg,SparkDataFrame-method
#' @rdname summarize
#' @name agg
#' @export
#' @note agg since 1.4.0
setMethod("agg",
signature(x = "SparkDataFrame"),
function(x, ...) {
agg(groupBy(x), ...)
})
#' @rdname summarize
#' @name summarize
#' @aliases summarize,SparkDataFrame-method
#' @note summarize since 1.4.0
setMethod("summarize",
signature(x = "SparkDataFrame"),
function(x, ...) {
agg(x, ...)
})
dapplyInternal <- function(x, func, schema) {
if (is.character(schema)) {
schema <- structType(schema)
}
packageNamesArr <- serialize(.sparkREnv[[".packages"]],
connection = NULL)
broadcastArr <- lapply(ls(.broadcastNames),
function(name) { get(name, .broadcastNames) })
sdf <- callJStatic(
"org.apache.spark.sql.api.r.SQLUtils",
"dapply",
x@sdf,
serialize(cleanClosure(func), connection = NULL),
packageNamesArr,
broadcastArr,
if (is.null(schema)) { schema } else { schema$jobj })
dataFrame(sdf)
}
setClassUnion("characterOrstructType", c("character", "structType"))
#' dapply
#'
#' Apply a function to each partition of a SparkDataFrame.
#'
#' @param x A SparkDataFrame
#' @param func A function to be applied to each partition of the SparkDataFrame.
#' func should have only one parameter, to which a R data.frame corresponds
#' to each partition will be passed.
#' The output of func should be a R data.frame.
#' @param schema The schema of the resulting SparkDataFrame after the function is applied.
#' It must match the output of func. Since Spark 2.3, the DDL-formatted string
#' is also supported for the schema.
#' @family SparkDataFrame functions
#' @rdname dapply
#' @aliases dapply,SparkDataFrame,function,characterOrstructType-method
#' @name dapply
#' @seealso \link{dapplyCollect}
#' @export
#' @examples
#' \dontrun{
#' df <- createDataFrame(iris)
#' df1 <- dapply(df, function(x) { x }, schema(df))
#' collect(df1)
#'
#' # filter and add a column
#' df <- createDataFrame(
#' list(list(1L, 1, "1"), list(2L, 2, "2"), list(3L, 3, "3")),
#' c("a", "b", "c"))
#' schema <- structType(structField("a", "integer"), structField("b", "double"),
#' structField("c", "string"), structField("d", "integer"))
#' df1 <- dapply(
#' df,
#' function(x) {
#' y <- x[x[1] > 1, ]
#' y <- cbind(y, y[1] + 1L)
#' },
#' schema)
#'
#' # The schema also can be specified in a DDL-formatted string.
#' schema <- "a INT, d DOUBLE, c STRING, d INT"
#' df1 <- dapply(
#' df,
#' function(x) {
#' y <- x[x[1] > 1, ]
#' y <- cbind(y, y[1] + 1L)
#' },
#' schema)
#'
#' collect(df1)
#' # the result
#' # a b c d
#' # 1 2 2 2 3
#' # 2 3 3 3 4
#' }
#' @note dapply since 2.0.0
setMethod("dapply",
signature(x = "SparkDataFrame", func = "function", schema = "characterOrstructType"),
function(x, func, schema) {
dapplyInternal(x, func, schema)
})
#' dapplyCollect
#'
#' Apply a function to each partition of a SparkDataFrame and collect the result back
#' to R as a data.frame.
#'
#' @param x A SparkDataFrame
#' @param func A function to be applied to each partition of the SparkDataFrame.
#' func should have only one parameter, to which a R data.frame corresponds
#' to each partition will be passed.
#' The output of func should be a R data.frame.
#' @family SparkDataFrame functions
#' @rdname dapplyCollect
#' @aliases dapplyCollect,SparkDataFrame,function-method
#' @name dapplyCollect
#' @seealso \link{dapply}
#' @export
#' @examples
#' \dontrun{
#' df <- createDataFrame(iris)
#' ldf <- dapplyCollect(df, function(x) { x })
#'
#' # filter and add a column
#' df <- createDataFrame(
#' list(list(1L, 1, "1"), list(2L, 2, "2"), list(3L, 3, "3")),
#' c("a", "b", "c"))
#' ldf <- dapplyCollect(
#' df,
#' function(x) {
#' y <- x[x[1] > 1, ]
#' y <- cbind(y, y[1] + 1L)
#' })
#' # the result
#' # a b c d
#' # 2 2 2 3
#' # 3 3 3 4
#' }
#' @note dapplyCollect since 2.0.0
setMethod("dapplyCollect",
signature(x = "SparkDataFrame", func = "function"),
function(x, func) {
df <- dapplyInternal(x, func, NULL)
content <- callJMethod(df@sdf, "collect")
# content is a list of items of struct type. Each item has a single field
# which is a serialized data.frame corresponds to one partition of the
# SparkDataFrame.
ldfs <- lapply(content, function(x) { unserialize(x[[1]]) })
ldf <- do.call(rbind, ldfs)
row.names(ldf) <- NULL
ldf
})
#' gapply
#'
#' Groups the SparkDataFrame using the specified columns and applies the R function to each
#' group.
#'
#' @param cols grouping columns.
#' @param func a function to be applied to each group partition specified by grouping
#' column of the SparkDataFrame. The function \code{func} takes as argument
#' a key - grouping columns and a data frame - a local R data.frame.
#' The output of \code{func} is a local R data.frame.
#' @param schema the schema of the resulting SparkDataFrame after the function is applied.
#' The schema must match to output of \code{func}. It has to be defined for each
#' output column with preferred output column name and corresponding data type.
#' Since Spark 2.3, the DDL-formatted string is also supported for the schema.
#' @return A SparkDataFrame.
#' @family SparkDataFrame functions
#' @aliases gapply,SparkDataFrame-method
#' @rdname gapply
#' @name gapply
#' @seealso \link{gapplyCollect}
#' @export
#' @examples
#'
#' \dontrun{
#' Computes the arithmetic mean of the second column by grouping
#' on the first and third columns. Output the grouping values and the average.
#'
#' df <- createDataFrame (
#' list(list(1L, 1, "1", 0.1), list(1L, 2, "1", 0.2), list(3L, 3, "3", 0.3)),
#' c("a", "b", "c", "d"))
#'
#' Here our output contains three columns, the key which is a combination of two
#' columns with data types integer and string and the mean which is a double.
#' schema <- structType(structField("a", "integer"), structField("c", "string"),
#' structField("avg", "double"))
#' result <- gapply(
#' df,
#' c("a", "c"),
#' function(key, x) {
#' y <- data.frame(key, mean(x$b), stringsAsFactors = FALSE)
#' }, schema)
#'
#' The schema also can be specified in a DDL-formatted string.
#' schema <- "a INT, c STRING, avg DOUBLE"
#' result <- gapply(
#' df,
#' c("a", "c"),
#' function(key, x) {
#' y <- data.frame(key, mean(x$b), stringsAsFactors = FALSE)
#' }, schema)
#'
#' We can also group the data and afterwards call gapply on GroupedData.
#' For Example:
#' gdf <- group_by(df, "a", "c")
#' result <- gapply(
#' gdf,
#' function(key, x) {
#' y <- data.frame(key, mean(x$b), stringsAsFactors = FALSE)
#' }, schema)
#' collect(result)
#'
#' Result
#' ------
#' a c avg
#' 3 3 3.0
#' 1 1 1.5
#'
#' Fits linear models on iris dataset by grouping on the 'Species' column and
#' using 'Sepal_Length' as a target variable, 'Sepal_Width', 'Petal_Length'
#' and 'Petal_Width' as training features.
#'
#' df <- createDataFrame (iris)
#' schema <- structType(structField("(Intercept)", "double"),
#' structField("Sepal_Width", "double"),structField("Petal_Length", "double"),
#' structField("Petal_Width", "double"))
#' df1 <- gapply(
#' df,
#' df$"Species",
#' function(key, x) {
#' m <- suppressWarnings(lm(Sepal_Length ~
#' Sepal_Width + Petal_Length + Petal_Width, x))
#' data.frame(t(coef(m)))
#' }, schema)
#' collect(df1)
#'
#' Result
#' ---------
#' Model (Intercept) Sepal_Width Petal_Length Petal_Width
#' 1 0.699883 0.3303370 0.9455356 -0.1697527
#' 2 1.895540 0.3868576 0.9083370 -0.6792238
#' 3 2.351890 0.6548350 0.2375602 0.2521257
#'
#'}
#' @note gapply(SparkDataFrame) since 2.0.0
setMethod("gapply",
signature(x = "SparkDataFrame"),
function(x, cols, func, schema) {
grouped <- do.call("groupBy", c(x, cols))
gapply(grouped, func, schema)
})
#' gapplyCollect
#'
#' Groups the SparkDataFrame using the specified columns, applies the R function to each
#' group and collects the result back to R as data.frame.
#'
#' @param cols grouping columns.
#' @param func a function to be applied to each group partition specified by grouping
#' column of the SparkDataFrame. The function \code{func} takes as argument
#' a key - grouping columns and a data frame - a local R data.frame.
#' The output of \code{func} is a local R data.frame.
#' @return A data.frame.
#' @family SparkDataFrame functions
#' @aliases gapplyCollect,SparkDataFrame-method
#' @rdname gapplyCollect
#' @name gapplyCollect
#' @seealso \link{gapply}
#' @export
#' @examples
#'
#' \dontrun{
#' Computes the arithmetic mean of the second column by grouping
#' on the first and third columns. Output the grouping values and the average.
#'
#' df <- createDataFrame (
#' list(list(1L, 1, "1", 0.1), list(1L, 2, "1", 0.2), list(3L, 3, "3", 0.3)),
#' c("a", "b", "c", "d"))
#'
#' result <- gapplyCollect(
#' df,
#' c("a", "c"),
#' function(key, x) {
#' y <- data.frame(key, mean(x$b), stringsAsFactors = FALSE)
#' colnames(y) <- c("key_a", "key_c", "mean_b")
#' y
#' })
#'
#' We can also group the data and afterwards call gapply on GroupedData.
#' For Example:
#' gdf <- group_by(df, "a", "c")
#' result <- gapplyCollect(
#' gdf,
#' function(key, x) {
#' y <- data.frame(key, mean(x$b), stringsAsFactors = FALSE)
#' colnames(y) <- c("key_a", "key_c", "mean_b")
#' y
#' })
#'
#' Result
#' ------
#' key_a key_c mean_b
#' 3 3 3.0
#' 1 1 1.5
#'
#' Fits linear models on iris dataset by grouping on the 'Species' column and
#' using 'Sepal_Length' as a target variable, 'Sepal_Width', 'Petal_Length'
#' and 'Petal_Width' as training features.
#'
#' df <- createDataFrame (iris)
#' result <- gapplyCollect(
#' df,
#' df$"Species",
#' function(key, x) {
#' m <- suppressWarnings(lm(Sepal_Length ~
#' Sepal_Width + Petal_Length + Petal_Width, x))
#' data.frame(t(coef(m)))
#' })
#'
#' Result
#'---------
#' Model X.Intercept. Sepal_Width Petal_Length Petal_Width
#' 1 0.699883 0.3303370 0.9455356 -0.1697527
#' 2 1.895540 0.3868576 0.9083370 -0.6792238
#' 3 2.351890 0.6548350 0.2375602 0.2521257
#'
#'}
#' @note gapplyCollect(SparkDataFrame) since 2.0.0
setMethod("gapplyCollect",
signature(x = "SparkDataFrame"),
function(x, cols, func) {
grouped <- do.call("groupBy", c(x, cols))
gapplyCollect(grouped, func)
})
############################## RDD Map Functions ##################################
# All of the following functions mirror the existing RDD map functions, #
# but allow for use with DataFrames by first converting to an RRDD before calling #
# the requested map function. #
###################################################################################
#' @rdname lapply
#' @noRd
setMethod("lapply",
signature(X = "SparkDataFrame", FUN = "function"),
function(X, FUN) {
rdd <- toRDD(X)
lapply(rdd, FUN)
})
#' @rdname lapply
#' @noRd
setMethod("map",
signature(X = "SparkDataFrame", FUN = "function"),
function(X, FUN) {
lapply(X, FUN)
})
#' @rdname flatMap
#' @noRd
setMethod("flatMap",
signature(X = "SparkDataFrame", FUN = "function"),
function(X, FUN) {
rdd <- toRDD(X)
flatMap(rdd, FUN)
})
#' @rdname lapplyPartition
#' @noRd
setMethod("lapplyPartition",
signature(X = "SparkDataFrame", FUN = "function"),
function(X, FUN) {
rdd <- toRDD(X)
lapplyPartition(rdd, FUN)
})
#' @rdname lapplyPartition
#' @noRd
setMethod("mapPartitions",
signature(X = "SparkDataFrame", FUN = "function"),
function(X, FUN) {
lapplyPartition(X, FUN)
})
#' @rdname foreach
#' @noRd
setMethod("foreach",
signature(x = "SparkDataFrame", func = "function"),
function(x, func) {
rdd <- toRDD(x)
foreach(rdd, func)
})
#' @rdname foreach
#' @noRd
setMethod("foreachPartition",
signature(x = "SparkDataFrame", func = "function"),
function(x, func) {
rdd <- toRDD(x)
foreachPartition(rdd, func)
})
############################## SELECT ##################################
getColumn <- function(x, c) {
column(callJMethod(x@sdf, "col", c))
}
setColumn <- function(x, c, value) {
if (class(value) != "Column" && !is.null(value)) {
if (isAtomicLengthOne(value)) {
value <- lit(value)
} else {
stop("value must be a Column, literal value as atomic in length of 1, or NULL")
}
}
if (is.null(value)) {
nx <- drop(x, c)
} else {
nx <- withColumn(x, c, value)
}
nx
}
#' @param name name of a Column (without being wrapped by \code{""}).
#' @rdname select
#' @name $
#' @aliases $,SparkDataFrame-method
#' @note $ since 1.4.0
setMethod("$", signature(x = "SparkDataFrame"),
function(x, name) {
getColumn(x, name)
})
#' @param value a Column or an atomic vector in the length of 1 as literal value, or \code{NULL}.
#' If \code{NULL}, the specified Column is dropped.
#' @rdname select
#' @name $<-
#' @aliases $<-,SparkDataFrame-method
#' @note $<- since 1.4.0
setMethod("$<-", signature(x = "SparkDataFrame"),
function(x, name, value) {
nx <- setColumn(x, name, value)
x@sdf <- nx@sdf
x
})
setClassUnion("numericOrcharacter", c("numeric", "character"))
#' @rdname subset
#' @name [[
#' @aliases [[,SparkDataFrame,numericOrcharacter-method
#' @note [[ since 1.4.0
setMethod("[[", signature(x = "SparkDataFrame", i = "numericOrcharacter"),
function(x, i) {
if (length(i) > 1) {
warning("Subset index has length > 1. Only the first index is used.")
i <- i[1]
}
if (is.numeric(i)) {
cols <- columns(x)
i <- cols[[i]]
}
getColumn(x, i)
})
#' @rdname subset
#' @name [[<-
#' @aliases [[<-,SparkDataFrame,numericOrcharacter-method
#' @note [[<- since 2.1.1
setMethod("[[<-", signature(x = "SparkDataFrame", i = "numericOrcharacter"),
function(x, i, value) {
if (length(i) > 1) {
warning("Subset index has length > 1. Only the first index is used.")
i <- i[1]
}
if (is.numeric(i)) {
cols <- columns(x)
i <- cols[[i]]
}
nx <- setColumn(x, i, value)
x@sdf <- nx@sdf
x
})
#' @rdname subset
#' @name [
#' @aliases [,SparkDataFrame-method
#' @note [ since 1.4.0
setMethod("[", signature(x = "SparkDataFrame"),
function(x, i, j, ..., drop = F) {
# Perform filtering first if needed
filtered <- if (missing(i)) {
x
} else {
if (class(i) != "Column") {
stop(paste0("Expressions other than filtering predicates are not supported ",
"in the first parameter of extract operator [ or subset() method."))
}
filter(x, i)
}
# If something is to be projected, then do so on the filtered SparkDataFrame
if (missing(j)) {
filtered
} else {
if (is.numeric(j)) {
cols <- columns(filtered)
j <- cols[j]
}
if (length(j) > 1) {
j <- as.list(j)
}
selected <- select(filtered, j)
# Acknowledge parameter drop. Return a Column or SparkDataFrame accordingly
if (ncol(selected) == 1 & drop == T) {
getColumn(selected, names(selected))
} else {
selected
}
}
})
#' Subset
#'
#' Return subsets of SparkDataFrame according to given conditions
#' @param x a SparkDataFrame.
#' @param i,subset (Optional) a logical expression to filter on rows.
#' For extract operator [[ and replacement operator [[<-, the indexing parameter for
#' a single Column.
#' @param j,select expression for the single Column or a list of columns to select from the
#' SparkDataFrame.
#' @param drop if TRUE, a Column will be returned if the resulting dataset has only one column.
#' Otherwise, a SparkDataFrame will always be returned.
#' @param value a Column or an atomic vector in the length of 1 as literal value, or \code{NULL}.
#' If \code{NULL}, the specified Column is dropped.
#' @param ... currently not used.
#' @return A new SparkDataFrame containing only the rows that meet the condition with selected
#' columns.
#' @export
#' @family SparkDataFrame functions
#' @aliases subset,SparkDataFrame-method
#' @seealso \link{withColumn}
#' @rdname subset
#' @name subset
#' @family subsetting functions
#' @examples
#' \dontrun{
#' # Columns can be selected using [[ and [
#' df[[2]] == df[["age"]]
#' df[,2] == df[,"age"]
#' df[,c("name", "age")]
#' # Or to filter rows
#' df[df$age > 20,]
#' # SparkDataFrame can be subset on both rows and Columns
#' df[df$name == "Smith", c(1,2)]
#' df[df$age %in% c(19, 30), 1:2]
#' subset(df, df$age %in% c(19, 30), 1:2)
#' subset(df, df$age %in% c(19), select = c(1,2))
#' subset(df, select = c(1,2))
#' # Columns can be selected and set
#' df[["age"]] <- 23
#' df[[1]] <- df$age
#' df[[2]] <- NULL # drop column
#' }
#' @note subset since 1.5.0
setMethod("subset", signature(x = "SparkDataFrame"),
function(x, subset, select, drop = F, ...) {
if (missing(subset)) {
x[, select, drop = drop, ...]
} else {
x[subset, select, drop = drop, ...]
}
})
#' Select
#'
#' Selects a set of columns with names or Column expressions.
#' @param x a SparkDataFrame.
#' @param col a list of columns or single Column or name.
#' @param ... additional column(s) if only one column is specified in \code{col}.
#' If more than one column is assigned in \code{col}, \code{...}
#' should be left empty.
#' @return A new SparkDataFrame with selected columns.
#' @export
#' @family SparkDataFrame functions
#' @rdname select
#' @aliases select,SparkDataFrame,character-method
#' @name select
#' @family subsetting functions
#' @examples
#' \dontrun{
#' select(df, "*")
#' select(df, "col1", "col2")
#' select(df, df$name, df$age + 1)
#' select(df, c("col1", "col2"))
#' select(df, list(df$name, df$age + 1))
#' # Similar to R data frames columns can also be selected using $
#' df[,df$age]
#' }
#' @note select(SparkDataFrame, character) since 1.4.0
setMethod("select", signature(x = "SparkDataFrame", col = "character"),
function(x, col, ...) {
if (length(col) > 1) {
if (length(list(...)) > 0) {
stop("To select multiple columns, use a character vector or list for col")
}
select(x, as.list(col))
} else {
sdf <- callJMethod(x@sdf, "select", col, list(...))
dataFrame(sdf)
}
})
#' @rdname select
#' @export
#' @aliases select,SparkDataFrame,Column-method
#' @note select(SparkDataFrame, Column) since 1.4.0
setMethod("select", signature(x = "SparkDataFrame", col = "Column"),
function(x, col, ...) {
jcols <- lapply(list(col, ...), function(c) {
c@jc
})
sdf <- callJMethod(x@sdf, "select", jcols)
dataFrame(sdf)
})
#' @rdname select
#' @export
#' @aliases select,SparkDataFrame,list-method
#' @note select(SparkDataFrame, list) since 1.4.0
setMethod("select",
signature(x = "SparkDataFrame", col = "list"),
function(x, col) {
cols <- lapply(col, function(c) {
if (class(c) == "Column") {
c@jc
} else {
col(c)@jc
}
})
sdf <- callJMethod(x@sdf, "select", cols)
dataFrame(sdf)
})
#' SelectExpr
#'
#' Select from a SparkDataFrame using a set of SQL expressions.
#'
#' @param x A SparkDataFrame to be selected from.
#' @param expr A string containing a SQL expression
#' @param ... Additional expressions
#' @return A SparkDataFrame
#' @family SparkDataFrame functions
#' @aliases selectExpr,SparkDataFrame,character-method
#' @rdname selectExpr
#' @name selectExpr
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' selectExpr(df, "col1", "(col2 * 5) as newCol")
#' }
#' @note selectExpr since 1.4.0
setMethod("selectExpr",
signature(x = "SparkDataFrame", expr = "character"),
function(x, expr, ...) {
exprList <- list(expr, ...)
sdf <- callJMethod(x@sdf, "selectExpr", exprList)
dataFrame(sdf)
})
#' WithColumn
#'
#' Return a new SparkDataFrame by adding a column or replacing the existing column
#' that has the same name.
#'
#' @param x a SparkDataFrame.
#' @param colName a column name.
#' @param col a Column expression, or an atomic vector in the length of 1 as literal value.
#' @return A SparkDataFrame with the new column added or the existing column replaced.
#' @family SparkDataFrame functions
#' @aliases withColumn,SparkDataFrame,character-method
#' @rdname withColumn
#' @name withColumn
#' @seealso \link{rename} \link{mutate} \link{subset}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' newDF <- withColumn(df, "newCol", df$col1 * 5)
#' # Replace an existing column
#' newDF2 <- withColumn(newDF, "newCol", newDF$col1)
#' newDF3 <- withColumn(newDF, "newCol", 42)
#' # Use extract operator to set an existing or new column
#' df[["age"]] <- 23
#' df[[2]] <- df$col1
#' df[[2]] <- NULL # drop column
#' }
#' @note withColumn since 1.4.0
setMethod("withColumn",
signature(x = "SparkDataFrame", colName = "character"),
function(x, colName, col) {
if (class(col) != "Column") {
if (!isAtomicLengthOne(col)) stop("Literal value must be atomic in length of 1")
col <- lit(col)
}
sdf <- callJMethod(x@sdf, "withColumn", colName, col@jc)
dataFrame(sdf)
})
#' Mutate
#'
#' Return a new SparkDataFrame with the specified columns added or replaced.
#'
#' @param .data a SparkDataFrame.
#' @param ... additional column argument(s) each in the form name = col.
#' @return A new SparkDataFrame with the new columns added or replaced.
#' @family SparkDataFrame functions
#' @aliases mutate,SparkDataFrame-method
#' @rdname mutate
#' @name mutate
#' @seealso \link{rename} \link{withColumn}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' newDF <- mutate(df, newCol = df$col1 * 5, newCol2 = df$col1 * 2)
#' names(newDF) # Will contain newCol, newCol2
#' newDF2 <- transform(df, newCol = df$col1 / 5, newCol2 = df$col1 * 2)
#'
#' df <- createDataFrame(list(list("Andy", 30L), list("Justin", 19L)), c("name", "age"))
#' # Replace the "age" column
#' df1 <- mutate(df, age = df$age + 1L)
#' }
#' @note mutate since 1.4.0
setMethod("mutate",
signature(.data = "SparkDataFrame"),
function(.data, ...) {
x <- .data
cols <- list(...)
if (length(cols) <= 0) {
return(x)
}
lapply(cols, function(col) {
stopifnot(class(col) == "Column")
})
# Check if there is any duplicated column name in the DataFrame
dfCols <- columns(x)
if (length(unique(dfCols)) != length(dfCols)) {
stop("Error: found duplicated column name in the DataFrame")
}
# TODO: simplify the implementation of this method after SPARK-12225 is resolved.
# For named arguments, use the names for arguments as the column names
# For unnamed arguments, use the argument symbols as the column names
args <- sapply(substitute(list(...))[-1], deparse)
ns <- names(cols)
if (!is.null(ns)) {
lapply(seq_along(args), function(i) {
if (ns[[i]] != "") {
args[[i]] <<- ns[[i]]
}
})
}
ns <- args
# The last column of the same name in the specific columns takes effect
deDupCols <- list()
for (i in 1:length(cols)) {
deDupCols[[ns[[i]]]] <- alias(cols[[i]], ns[[i]])
}
# Construct the column list for projection
colList <- lapply(dfCols, function(col) {
if (!is.null(deDupCols[[col]])) {
# Replace existing column
tmpCol <- deDupCols[[col]]
deDupCols[[col]] <<- NULL
tmpCol
} else {
col(col)
}
})
do.call(select, c(x, colList, deDupCols))
})
#' @param _data a SparkDataFrame.
#' @export
#' @rdname mutate
#' @aliases transform,SparkDataFrame-method
#' @name transform
#' @note transform since 1.5.0
setMethod("transform",
signature(`_data` = "SparkDataFrame"),
function(`_data`, ...) {
mutate(`_data`, ...)
})
#' rename
#'
#' Rename an existing column in a SparkDataFrame.
#'
#' @param x A SparkDataFrame
#' @param existingCol The name of the column you want to change.
#' @param newCol The new column name.
#' @return A SparkDataFrame with the column name changed.
#' @family SparkDataFrame functions
#' @rdname rename
#' @name withColumnRenamed
#' @aliases withColumnRenamed,SparkDataFrame,character,character-method
#' @seealso \link{mutate}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' newDF <- withColumnRenamed(df, "col1", "newCol1")
#' }
#' @note withColumnRenamed since 1.4.0
setMethod("withColumnRenamed",
signature(x = "SparkDataFrame", existingCol = "character", newCol = "character"),
function(x, existingCol, newCol) {
cols <- lapply(columns(x), function(c) {
if (c == existingCol) {
alias(col(c), newCol)
} else {
col(c)
}
})
select(x, cols)
})
#' @param ... A named pair of the form new_column_name = existing_column
#' @rdname rename
#' @name rename
#' @aliases rename,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' newDF <- rename(df, col1 = df$newCol1)
#' }
#' @note rename since 1.4.0
setMethod("rename",
signature(x = "SparkDataFrame"),
function(x, ...) {
renameCols <- list(...)
stopifnot(length(renameCols) > 0)
stopifnot(class(renameCols[[1]]) == "Column")
newNames <- names(renameCols)
oldNames <- lapply(renameCols, function(col) {
callJMethod(col@jc, "toString")
})
cols <- lapply(columns(x), function(c) {
if (c %in% oldNames) {
alias(col(c), newNames[[match(c, oldNames)]])
} else {
col(c)
}
})
select(x, cols)
})
setClassUnion("characterOrColumn", c("character", "Column"))
#' Arrange Rows by Variables
#'
#' Sort a SparkDataFrame by the specified column(s).
#'
#' @param x a SparkDataFrame to be sorted.
#' @param col a character or Column object indicating the fields to sort on
#' @param ... additional sorting fields
#' @param decreasing a logical argument indicating sorting order for columns when
#' a character vector is specified for col
#' @return A SparkDataFrame where all elements are sorted.
#' @family SparkDataFrame functions
#' @aliases arrange,SparkDataFrame,Column-method
#' @rdname arrange
#' @name arrange
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' arrange(df, df$col1)
#' arrange(df, asc(df$col1), desc(abs(df$col2)))
#' arrange(df, "col1", decreasing = TRUE)
#' arrange(df, "col1", "col2", decreasing = c(TRUE, FALSE))
#' }
#' @note arrange(SparkDataFrame, Column) since 1.4.0
setMethod("arrange",
signature(x = "SparkDataFrame", col = "Column"),
function(x, col, ...) {
jcols <- lapply(list(col, ...), function(c) {
c@jc
})
sdf <- callJMethod(x@sdf, "sort", jcols)
dataFrame(sdf)
})
#' @rdname arrange
#' @name arrange
#' @aliases arrange,SparkDataFrame,character-method
#' @export
#' @note arrange(SparkDataFrame, character) since 1.4.0
setMethod("arrange",
signature(x = "SparkDataFrame", col = "character"),
function(x, col, ..., decreasing = FALSE) {
# all sorting columns
by <- list(col, ...)
if (length(decreasing) == 1) {
# in case only 1 boolean argument - decreasing value is specified,
# it will be used for all columns
decreasing <- rep(decreasing, length(by))
} else if (length(decreasing) != length(by)) {
stop("Arguments 'col' and 'decreasing' must have the same length")
}
# builds a list of columns of type Column
# example: [[1]] Column Species ASC
# [[2]] Column Petal_Length DESC
jcols <- lapply(seq_len(length(decreasing)), function(i){
if (decreasing[[i]]) {
desc(getColumn(x, by[[i]]))
} else {
asc(getColumn(x, by[[i]]))
}
})
do.call("arrange", c(x, jcols))
})
#' @rdname arrange
#' @aliases orderBy,SparkDataFrame,characterOrColumn-method
#' @export
#' @note orderBy(SparkDataFrame, characterOrColumn) since 1.4.0
setMethod("orderBy",
signature(x = "SparkDataFrame", col = "characterOrColumn"),
function(x, col, ...) {
arrange(x, col, ...)
})
#' Filter
#'
#' Filter the rows of a SparkDataFrame according to a given condition.
#'
#' @param x A SparkDataFrame to be sorted.
#' @param condition The condition to filter on. This may either be a Column expression
#' or a string containing a SQL statement
#' @return A SparkDataFrame containing only the rows that meet the condition.
#' @family SparkDataFrame functions
#' @aliases filter,SparkDataFrame,characterOrColumn-method
#' @rdname filter
#' @name filter
#' @family subsetting functions
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' filter(df, "col1 > 0")
#' filter(df, df$col2 != "abcdefg")
#' }
#' @note filter since 1.4.0
setMethod("filter",
signature(x = "SparkDataFrame", condition = "characterOrColumn"),
function(x, condition) {
if (class(condition) == "Column") {
condition <- condition@jc
}
sdf <- callJMethod(x@sdf, "filter", condition)
dataFrame(sdf)
})
#' @rdname filter
#' @name where
#' @aliases where,SparkDataFrame,characterOrColumn-method
#' @note where since 1.4.0
setMethod("where",
signature(x = "SparkDataFrame", condition = "characterOrColumn"),
function(x, condition) {
filter(x, condition)
})
#' dropDuplicates
#'
#' Returns a new SparkDataFrame with duplicate rows removed, considering only
#' the subset of columns.
#'
#' @param x A SparkDataFrame.
#' @param ... A character vector of column names or string column names.
#' If the first argument contains a character vector, the followings are ignored.
#' @return A SparkDataFrame with duplicate rows removed.
#' @family SparkDataFrame functions
#' @aliases dropDuplicates,SparkDataFrame-method
#' @rdname dropDuplicates
#' @name dropDuplicates
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' dropDuplicates(df)
#' dropDuplicates(df, "col1", "col2")
#' dropDuplicates(df, c("col1", "col2"))
#' }
#' @note dropDuplicates since 2.0.0
setMethod("dropDuplicates",
signature(x = "SparkDataFrame"),
function(x, ...) {
cols <- list(...)
if (length(cols) == 0) {
sdf <- callJMethod(x@sdf, "dropDuplicates", as.list(columns(x)))
} else {
if (!all(sapply(cols, function(c) { is.character(c) }))) {
stop("all columns names should be characters")
}
col <- cols[[1]]
if (length(col) > 1) {
sdf <- callJMethod(x@sdf, "dropDuplicates", as.list(col))
} else {
sdf <- callJMethod(x@sdf, "dropDuplicates", cols)
}
}
dataFrame(sdf)
})
#' Join
#'
#' Joins two SparkDataFrames based on the given join expression.
#'
#' @param x A SparkDataFrame
#' @param y A SparkDataFrame
#' @param joinExpr (Optional) The expression used to perform the join. joinExpr must be a
#' Column expression. If joinExpr is omitted, the default, inner join is attempted and an error is
#' thrown if it would be a Cartesian Product. For Cartesian join, use crossJoin instead.
#' @param joinType The type of join to perform, default 'inner'.
#' Must be one of: 'inner', 'cross', 'outer', 'full', 'full_outer',
#' 'left', 'left_outer', 'right', 'right_outer', 'left_semi', or 'left_anti'.
#' @return A SparkDataFrame containing the result of the join operation.
#' @family SparkDataFrame functions
#' @aliases join,SparkDataFrame,SparkDataFrame-method
#' @rdname join
#' @name join
#' @seealso \link{merge} \link{crossJoin}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df1 <- read.json(path)
#' df2 <- read.json(path2)
#' join(df1, df2, df1$col1 == df2$col2) # Performs an inner join based on expression
#' join(df1, df2, df1$col1 == df2$col2, "right_outer")
#' join(df1, df2) # Attempts an inner join
#' }
#' @note join since 1.4.0
setMethod("join",
signature(x = "SparkDataFrame", y = "SparkDataFrame"),
function(x, y, joinExpr = NULL, joinType = NULL) {
if (is.null(joinExpr)) {
# this may not fail until the planner checks for Cartesian join later on.
sdf <- callJMethod(x@sdf, "join", y@sdf)
} else {
if (class(joinExpr) != "Column") stop("joinExpr must be a Column")
if (is.null(joinType)) {
sdf <- callJMethod(x@sdf, "join", y@sdf, joinExpr@jc)
} else {
if (joinType %in% c("inner", "cross",
"outer", "full", "fullouter", "full_outer",
"left", "leftouter", "left_outer",
"right", "rightouter", "right_outer",
"left_semi", "leftsemi", "left_anti", "leftanti")) {
joinType <- gsub("_", "", joinType)
sdf <- callJMethod(x@sdf, "join", y@sdf, joinExpr@jc, joinType)
} else {
stop("joinType must be one of the following types: ",
"'inner', 'cross', 'outer', 'full', 'full_outer',",
"'left', 'left_outer', 'right', 'right_outer',",
"'left_semi', or 'left_anti'.")
}
}
}
dataFrame(sdf)
})
#' CrossJoin
#'
#' Returns Cartesian Product on two SparkDataFrames.
#'
#' @param x A SparkDataFrame
#' @param y A SparkDataFrame
#' @return A SparkDataFrame containing the result of the join operation.
#' @family SparkDataFrame functions
#' @aliases crossJoin,SparkDataFrame,SparkDataFrame-method
#' @rdname crossJoin
#' @name crossJoin
#' @seealso \link{merge} \link{join}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df1 <- read.json(path)
#' df2 <- read.json(path2)
#' crossJoin(df1, df2) # Performs a Cartesian
#' }
#' @note crossJoin since 2.1.0
setMethod("crossJoin",
signature(x = "SparkDataFrame", y = "SparkDataFrame"),
function(x, y) {
sdf <- callJMethod(x@sdf, "crossJoin", y@sdf)
dataFrame(sdf)
})
#' Merges two data frames
#'
#' @name merge
#' @param x the first data frame to be joined.
#' @param y the second data frame to be joined.
#' @param by a character vector specifying the join columns. If by is not
#' specified, the common column names in \code{x} and \code{y} will be used.
#' If by or both by.x and by.y are explicitly set to NULL or of length 0, the Cartesian
#' Product of x and y will be returned.
#' @param by.x a character vector specifying the joining columns for x.
#' @param by.y a character vector specifying the joining columns for y.
#' @param all a boolean value setting \code{all.x} and \code{all.y}
#' if any of them are unset.
#' @param all.x a boolean value indicating whether all the rows in x should
#' be including in the join.
#' @param all.y a boolean value indicating whether all the rows in y should
#' be including in the join.
#' @param sort a logical argument indicating whether the resulting columns should be sorted.
#' @param suffixes a string vector of length 2 used to make colnames of
#' \code{x} and \code{y} unique.
#' The first element is appended to each colname of \code{x}.
#' The second element is appended to each colname of \code{y}.
#' @param ... additional argument(s) passed to the method.
#' @details If all.x and all.y are set to FALSE, a natural join will be returned. If
#' all.x is set to TRUE and all.y is set to FALSE, a left outer join will
#' be returned. If all.x is set to FALSE and all.y is set to TRUE, a right
#' outer join will be returned. If all.x and all.y are set to TRUE, a full
#' outer join will be returned.
#' @family SparkDataFrame functions
#' @aliases merge,SparkDataFrame,SparkDataFrame-method
#' @rdname merge
#' @seealso \link{join} \link{crossJoin}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df1 <- read.json(path)
#' df2 <- read.json(path2)
#' merge(df1, df2) # Performs an inner join by common columns
#' merge(df1, df2, by = "col1") # Performs an inner join based on expression
#' merge(df1, df2, by.x = "col1", by.y = "col2", all.y = TRUE)
#' merge(df1, df2, by.x = "col1", by.y = "col2", all.x = TRUE)
#' merge(df1, df2, by.x = "col1", by.y = "col2", all.x = TRUE, all.y = TRUE)
#' merge(df1, df2, by.x = "col1", by.y = "col2", all = TRUE, sort = FALSE)
#' merge(df1, df2, by = "col1", all = TRUE, suffixes = c("-X", "-Y"))
#' merge(df1, df2, by = NULL) # Performs a Cartesian join
#' }
#' @note merge since 1.5.0
setMethod("merge",
signature(x = "SparkDataFrame", y = "SparkDataFrame"),
function(x, y, by = intersect(names(x), names(y)), by.x = by, by.y = by,
all = FALSE, all.x = all, all.y = all,
sort = TRUE, suffixes = c("_x", "_y"), ...) {
if (length(suffixes) != 2) {
stop("suffixes must have length 2")
}
# join type is identified based on the values of all, all.x and all.y
# default join type is inner, according to R it should be natural but since it
# is not supported in spark inner join is used
joinType <- "inner"
if (all || (all.x && all.y)) {
joinType <- "outer"
} else if (all.x) {
joinType <- "left_outer"
} else if (all.y) {
joinType <- "right_outer"
}
# join expression is based on by.x, by.y if both by.x and by.y are not missing
# or on by, if by.x or by.y are missing or have different lengths
if (length(by.x) > 0 && length(by.x) == length(by.y)) {
joinX <- by.x
joinY <- by.y
} else if (length(by) > 0) {
# if join columns have the same name for both dataframes,
# they are used in join expression
joinX <- by
joinY <- by
} else {
# if by or both by.x and by.y have length 0, use Cartesian Product
joinRes <- crossJoin(x, y)
return(joinRes)
}
# sets alias for making colnames unique in dataframes 'x' and 'y'
colsX <- genAliasesForIntersectedCols(x, by, suffixes[1])
colsY <- genAliasesForIntersectedCols(y, by, suffixes[2])
# selects columns with their aliases from dataframes
# in case same column names are present in both data frames
xsel <- select(x, colsX)
ysel <- select(y, colsY)
# generates join conditions and adds them into a list
# it also considers alias names of the columns while generating join conditions
joinColumns <- lapply(seq_len(length(joinX)), function(i) {
colX <- joinX[[i]]
colY <- joinY[[i]]
if (colX %in% by) {
colX <- paste(colX, suffixes[1], sep = "")
}
if (colY %in% by) {
colY <- paste(colY, suffixes[2], sep = "")
}
colX <- getColumn(xsel, colX)
colY <- getColumn(ysel, colY)
colX == colY
})
# concatenates join columns with '&' and executes join
joinExpr <- Reduce("&", joinColumns)
joinRes <- join(xsel, ysel, joinExpr, joinType)
# sorts the result by 'by' columns if sort = TRUE
if (sort && length(by) > 0) {
colNameWithSuffix <- paste(by, suffixes[2], sep = "")
joinRes <- do.call("arrange", c(joinRes, colNameWithSuffix, decreasing = FALSE))
}
joinRes
})
#' Creates a list of columns by replacing the intersected ones with aliases
#'
#' Creates a list of columns by replacing the intersected ones with aliases.
#' The name of the alias column is formed by concatanating the original column name and a suffix.
#'
#' @param x a SparkDataFrame
#' @param intersectedColNames a list of intersected column names of the SparkDataFrame
#' @param suffix a suffix for the column name
#' @return list of columns
#' @noRd
genAliasesForIntersectedCols <- function(x, intersectedColNames, suffix) {
allColNames <- names(x)
# sets alias for making colnames unique in dataframe 'x'
cols <- lapply(allColNames, function(colName) {
col <- getColumn(x, colName)
if (colName %in% intersectedColNames) {
newJoin <- paste(colName, suffix, sep = "")
if (newJoin %in% allColNames){
stop("The following column name: ", newJoin, " occurs more than once in the 'DataFrame'.",
"Please use different suffixes for the intersected columns.")
}
col <- alias(col, newJoin)
}
col
})
cols
}
#' Return a new SparkDataFrame containing the union of rows
#'
#' Return a new SparkDataFrame containing the union of rows in this SparkDataFrame
#' and another SparkDataFrame. This is equivalent to \code{UNION ALL} in SQL.
#' Input SparkDataFrames can have different schemas (names and data types).
#'
#' Note: This does not remove duplicate rows across the two SparkDataFrames.
#' Also as standard in SQL, this function resolves columns by position (not by name).
#'
#' @param x A SparkDataFrame
#' @param y A SparkDataFrame
#' @return A SparkDataFrame containing the result of the union.
#' @family SparkDataFrame functions
#' @rdname union
#' @name union
#' @aliases union,SparkDataFrame,SparkDataFrame-method
#' @seealso \link{rbind} \link{unionByName}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df1 <- read.json(path)
#' df2 <- read.json(path2)
#' unioned <- union(df, df2)
#' unions <- rbind(df, df2, df3, df4)
#' }
#' @note union since 2.0.0
setMethod("union",
signature(x = "SparkDataFrame", y = "SparkDataFrame"),
function(x, y) {
unioned <- callJMethod(x@sdf, "union", y@sdf)
dataFrame(unioned)
})
#' unionAll is deprecated - use union instead
#' @rdname union
#' @name unionAll
#' @aliases unionAll,SparkDataFrame,SparkDataFrame-method
#' @export
#' @note unionAll since 1.4.0
setMethod("unionAll",
signature(x = "SparkDataFrame", y = "SparkDataFrame"),
function(x, y) {
.Deprecated("union")
union(x, y)
})
#' Return a new SparkDataFrame containing the union of rows, matched by column names
#'
#' Return a new SparkDataFrame containing the union of rows in this SparkDataFrame
#' and another SparkDataFrame. This is different from \code{union} function, and both
#' \code{UNION ALL} and \code{UNION DISTINCT} in SQL as column positions are not taken
#' into account. Input SparkDataFrames can have different data types in the schema.
#'
#' Note: This does not remove duplicate rows across the two SparkDataFrames.
#' This function resolves columns by name (not by position).
#'
#' @param x A SparkDataFrame
#' @param y A SparkDataFrame
#' @return A SparkDataFrame containing the result of the union.
#' @family SparkDataFrame functions
#' @rdname unionByName
#' @name unionByName
#' @aliases unionByName,SparkDataFrame,SparkDataFrame-method
#' @seealso \link{rbind} \link{union}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df1 <- select(createDataFrame(mtcars), "carb", "am", "gear")
#' df2 <- select(createDataFrame(mtcars), "am", "gear", "carb")
#' head(unionByName(df1, df2))
#' }
#' @note unionByName since 2.3.0
setMethod("unionByName",
signature(x = "SparkDataFrame", y = "SparkDataFrame"),
function(x, y) {
unioned <- callJMethod(x@sdf, "unionByName", y@sdf)
dataFrame(unioned)
})
#' Union two or more SparkDataFrames
#'
#' Union two or more SparkDataFrames by row. As in R's \code{rbind}, this method
#' requires that the input SparkDataFrames have the same column names.
#'
#' Note: This does not remove duplicate rows across the two SparkDataFrames.
#'
#' @param x a SparkDataFrame.
#' @param ... additional SparkDataFrame(s).
#' @param deparse.level currently not used (put here to match the signature of
#' the base implementation).
#' @return A SparkDataFrame containing the result of the union.
#' @family SparkDataFrame functions
#' @aliases rbind,SparkDataFrame-method
#' @rdname rbind
#' @name rbind
#' @seealso \link{union} \link{unionByName}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' unions <- rbind(df, df2, df3, df4)
#' }
#' @note rbind since 1.5.0
setMethod("rbind",
signature(... = "SparkDataFrame"),
function(x, ..., deparse.level = 1) {
nm <- lapply(list(x, ...), names)
if (length(unique(nm)) != 1) {
stop("Names of input data frames are different.")
}
if (nargs() == 3) {
union(x, ...)
} else {
union(x, Recall(..., deparse.level = 1))
}
})
#' Intersect
#'
#' Return a new SparkDataFrame containing rows only in both this SparkDataFrame
#' and another SparkDataFrame. This is equivalent to \code{INTERSECT} in SQL.
#'
#' @param x A SparkDataFrame
#' @param y A SparkDataFrame
#' @return A SparkDataFrame containing the result of the intersect.
#' @family SparkDataFrame functions
#' @aliases intersect,SparkDataFrame,SparkDataFrame-method
#' @rdname intersect
#' @name intersect
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df1 <- read.json(path)
#' df2 <- read.json(path2)
#' intersectDF <- intersect(df, df2)
#' }
#' @note intersect since 1.4.0
setMethod("intersect",
signature(x = "SparkDataFrame", y = "SparkDataFrame"),
function(x, y) {
intersected <- callJMethod(x@sdf, "intersect", y@sdf)
dataFrame(intersected)
})
#' except
#'
#' Return a new SparkDataFrame containing rows in this SparkDataFrame
#' but not in another SparkDataFrame. This is equivalent to \code{EXCEPT} in SQL.
#'
#' @param x a SparkDataFrame.
#' @param y a SparkDataFrame.
#' @return A SparkDataFrame containing the result of the except operation.
#' @family SparkDataFrame functions
#' @aliases except,SparkDataFrame,SparkDataFrame-method
#' @rdname except
#' @name except
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df1 <- read.json(path)
#' df2 <- read.json(path2)
#' exceptDF <- except(df, df2)
#' }
#' @rdname except
#' @export
#' @note except since 1.4.0
setMethod("except",
signature(x = "SparkDataFrame", y = "SparkDataFrame"),
function(x, y) {
excepted <- callJMethod(x@sdf, "except", y@sdf)
dataFrame(excepted)
})
#' Save the contents of SparkDataFrame to a data source.
#'
#' The data source is specified by the \code{source} and a set of options (...).
#' If \code{source} is not specified, the default data source configured by
#' spark.sql.sources.default will be used.
#'
#' Additionally, mode is used to specify the behavior of the save operation when data already
#' exists in the data source. There are four modes:
#' \itemize{
#' \item 'append': Contents of this SparkDataFrame are expected to be appended to existing data.
#' \item 'overwrite': Existing data is expected to be overwritten by the contents of this
#' SparkDataFrame.
#' \item 'error' or 'errorifexists': An exception is expected to be thrown.
#' \item 'ignore': The save operation is expected to not save the contents of the SparkDataFrame
#' and to not change the existing data.
#' }
#'
#' @param df a SparkDataFrame.
#' @param path a name for the table.
#' @param source a name for external data source.
#' @param mode one of 'append', 'overwrite', 'error', 'errorifexists', 'ignore'
#' save mode (it is 'error' by default)
#' @param ... additional argument(s) passed to the method.
#'
#' @family SparkDataFrame functions
#' @aliases write.df,SparkDataFrame-method
#' @rdname write.df
#' @name write.df
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' write.df(df, "myfile", "parquet", "overwrite")
#' saveDF(df, parquetPath2, "parquet", mode = "append", mergeSchema = TRUE)
#' }
#' @note write.df since 1.4.0
setMethod("write.df",
signature(df = "SparkDataFrame"),
function(df, path = NULL, source = NULL, mode = "error", ...) {
if (!is.null(path) && !is.character(path)) {
stop("path should be character, NULL or omitted.")
}
if (!is.null(source) && !is.character(source)) {
stop("source should be character, NULL or omitted. It is the datasource specified ",
"in 'spark.sql.sources.default' configuration by default.")
}
if (!is.character(mode)) {
stop("mode should be character or omitted. It is 'error' by default.")
}
if (is.null(source)) {
source <- getDefaultSqlSource()
}
write <- callJMethod(df@sdf, "write")
write <- callJMethod(write, "format", source)
write <- setWriteOptions(write, path = path, mode = mode, ...)
write <- handledCallJMethod(write, "save")
})
#' @rdname write.df
#' @name saveDF
#' @aliases saveDF,SparkDataFrame,character-method
#' @export
#' @note saveDF since 1.4.0
setMethod("saveDF",
signature(df = "SparkDataFrame", path = "character"),
function(df, path, source = NULL, mode = "error", ...) {
write.df(df, path, source, mode, ...)
})
#' Save the contents of the SparkDataFrame to a data source as a table
#'
#' The data source is specified by the \code{source} and a set of options (...).
#' If \code{source} is not specified, the default data source configured by
#' spark.sql.sources.default will be used.
#'
#' Additionally, mode is used to specify the behavior of the save operation when
#' data already exists in the data source. There are four modes: \cr
#' 'append': Contents of this SparkDataFrame are expected to be appended to existing data. \cr
#' 'overwrite': Existing data is expected to be overwritten by the contents of this
#' SparkDataFrame. \cr
#' 'error' or 'errorifexists': An exception is expected to be thrown. \cr
#' 'ignore': The save operation is expected to not save the contents of the SparkDataFrame
#' and to not change the existing data. \cr
#'
#' @param df a SparkDataFrame.
#' @param tableName a name for the table.
#' @param source a name for external data source.
#' @param mode one of 'append', 'overwrite', 'error', 'errorifexists', 'ignore'
#' save mode (it is 'error' by default)
#' @param ... additional option(s) passed to the method.
#'
#' @family SparkDataFrame functions
#' @aliases saveAsTable,SparkDataFrame,character-method
#' @rdname saveAsTable
#' @name saveAsTable
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' saveAsTable(df, "myfile")
#' }
#' @note saveAsTable since 1.4.0
setMethod("saveAsTable",
signature(df = "SparkDataFrame", tableName = "character"),
function(df, tableName, source = NULL, mode="error", ...) {
if (is.null(source)) {
source <- getDefaultSqlSource()
}
options <- varargsToStrEnv(...)
write <- callJMethod(df@sdf, "write")
write <- callJMethod(write, "format", source)
write <- setWriteMode(write, mode)
write <- callJMethod(write, "options", options)
invisible(callJMethod(write, "saveAsTable", tableName))
})
#' describe
#'
#' Computes statistics for numeric and string columns.
#' If no columns are given, this function computes statistics for all numerical or string columns.
#'
#' @param x a SparkDataFrame to be computed.
#' @param col a string of name.
#' @param ... additional expressions.
#' @return A SparkDataFrame.
#' @family SparkDataFrame functions
#' @aliases describe,SparkDataFrame,character-method describe,SparkDataFrame,ANY-method
#' @rdname describe
#' @name describe
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' describe(df)
#' describe(df, "col1")
#' describe(df, "col1", "col2")
#' }
#' @seealso See \link{summary} for expanded statistics and control over which statistics to compute.
#' @note describe(SparkDataFrame, character) since 1.4.0
setMethod("describe",
signature(x = "SparkDataFrame", col = "character"),
function(x, col, ...) {
colList <- list(col, ...)
sdf <- callJMethod(x@sdf, "describe", colList)
dataFrame(sdf)
})
#' @rdname describe
#' @name describe
#' @aliases describe,SparkDataFrame-method
#' @note describe(SparkDataFrame) since 1.4.0
setMethod("describe",
signature(x = "SparkDataFrame"),
function(x) {
sdf <- callJMethod(x@sdf, "describe", list())
dataFrame(sdf)
})
#' summary
#'
#' Computes specified statistics for numeric and string columns. Available statistics are:
#' \itemize{
#' \item count
#' \item mean
#' \item stddev
#' \item min
#' \item max
#' \item arbitrary approximate percentiles specified as a percentage (eg, "75%")
#' }
#' If no statistics are given, this function computes count, mean, stddev, min,
#' approximate quartiles (percentiles at 25%, 50%, and 75%), and max.
#' This function is meant for exploratory data analysis, as we make no guarantee about the
#' backward compatibility of the schema of the resulting Dataset. If you want to
#' programmatically compute summary statistics, use the \code{agg} function instead.
#'
#'
#' @param object a SparkDataFrame to be summarized.
#' @param ... (optional) statistics to be computed for all columns.
#' @return A SparkDataFrame.
#' @family SparkDataFrame functions
#' @rdname summary
#' @name summary
#' @aliases summary,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' summary(df)
#' summary(df, "min", "25%", "75%", "max")
#' summary(select(df, "age", "height"))
#' }
#' @note summary(SparkDataFrame) since 1.5.0
#' @note The statistics provided by \code{summary} were change in 2.3.0 use \link{describe} for
#' previous defaults.
#' @seealso \link{describe}
setMethod("summary",
signature(object = "SparkDataFrame"),
function(object, ...) {
statisticsList <- list(...)
sdf <- callJMethod(object@sdf, "summary", statisticsList)
dataFrame(sdf)
})
#' A set of SparkDataFrame functions working with NA values
#'
#' dropna, na.omit - Returns a new SparkDataFrame omitting rows with null values.
#'
#' @param x a SparkDataFrame.
#' @param how "any" or "all".
#' if "any", drop a row if it contains any nulls.
#' if "all", drop a row only if all its values are null.
#' if \code{minNonNulls} is specified, how is ignored.
#' @param minNonNulls if specified, drop rows that have less than
#' \code{minNonNulls} non-null values.
#' This overwrites the how parameter.
#' @param cols optional list of column names to consider. In \code{fillna},
#' columns specified in cols that do not have matching data
#' type are ignored. For example, if value is a character, and
#' subset contains a non-character column, then the non-character
#' column is simply ignored.
#' @return A SparkDataFrame.
#'
#' @family SparkDataFrame functions
#' @rdname nafunctions
#' @aliases dropna,SparkDataFrame-method
#' @name dropna
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' dropna(df)
#' }
#' @note dropna since 1.4.0
setMethod("dropna",
signature(x = "SparkDataFrame"),
function(x, how = c("any", "all"), minNonNulls = NULL, cols = NULL) {
how <- match.arg(how)
if (is.null(cols)) {
cols <- columns(x)
}
if (is.null(minNonNulls)) {
minNonNulls <- if (how == "any") { length(cols) } else { 1 }
}
naFunctions <- callJMethod(x@sdf, "na")
sdf <- callJMethod(naFunctions, "drop",
as.integer(minNonNulls), as.list(cols))
dataFrame(sdf)
})
#' @param object a SparkDataFrame.
#' @param ... further arguments to be passed to or from other methods.
#' @rdname nafunctions
#' @name na.omit
#' @aliases na.omit,SparkDataFrame-method
#' @export
#' @note na.omit since 1.5.0
setMethod("na.omit",
signature(object = "SparkDataFrame"),
function(object, how = c("any", "all"), minNonNulls = NULL, cols = NULL) {
dropna(object, how, minNonNulls, cols)
})
#' fillna - Replace null values.
#'
#' @param value value to replace null values with.
#' Should be an integer, numeric, character or named list.
#' If the value is a named list, then cols is ignored and
#' value must be a mapping from column name (character) to
#' replacement value. The replacement value must be an
#' integer, numeric or character.
#'
#' @rdname nafunctions
#' @name fillna
#' @aliases fillna,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' fillna(df, 1)
#' fillna(df, list("age" = 20, "name" = "unknown"))
#' }
#' @note fillna since 1.4.0
setMethod("fillna",
signature(x = "SparkDataFrame"),
function(x, value, cols = NULL) {
if (!(class(value) %in% c("integer", "numeric", "character", "list"))) {
stop("value should be an integer, numeric, character or named list.")
}
if (class(value) == "list") {
# Check column names in the named list
colNames <- names(value)
if (length(colNames) == 0 || !all(colNames != "")) {
stop("value should be an a named list with each name being a column name.")
}
# Check each item in the named list is of valid type
lapply(value, function(v) {
if (!(class(v) %in% c("integer", "numeric", "character"))) {
stop("Each item in value should be an integer, numeric or character.")
}
})
# Convert to the named list to an environment to be passed to JVM
valueMap <- convertNamedListToEnv(value)
# When value is a named list, caller is expected not to pass in cols
if (!is.null(cols)) {
warning("When value is a named list, cols is ignored!")
cols <- NULL
}
value <- valueMap
} else if (is.integer(value)) {
# Cast an integer to a numeric
value <- as.numeric(value)
}
naFunctions <- callJMethod(x@sdf, "na")
sdf <- if (length(cols) == 0) {
callJMethod(naFunctions, "fill", value)
} else {
callJMethod(naFunctions, "fill", value, as.list(cols))
}
dataFrame(sdf)
})
#' Download data from a SparkDataFrame into a R data.frame
#'
#' This function downloads the contents of a SparkDataFrame into an R's data.frame.
#' Since data.frames are held in memory, ensure that you have enough memory
#' in your system to accommodate the contents.
#'
#' @param x a SparkDataFrame.
#' @param row.names \code{NULL} or a character vector giving the row names for the data frame.
#' @param optional If \code{TRUE}, converting column names is optional.
#' @param ... additional arguments to pass to base::as.data.frame.
#' @return A data.frame.
#' @family SparkDataFrame functions
#' @aliases as.data.frame,SparkDataFrame-method
#' @rdname as.data.frame
#' @examples
#' \dontrun{
#' irisDF <- createDataFrame(iris)
#' df <- as.data.frame(irisDF[irisDF$Species == "setosa", ])
#' }
#' @note as.data.frame since 1.6.0
setMethod("as.data.frame",
signature(x = "SparkDataFrame"),
function(x, row.names = NULL, optional = FALSE, ...) {
as.data.frame(collect(x), row.names, optional, ...)
})
#' Attach SparkDataFrame to R search path
#'
#' The specified SparkDataFrame is attached to the R search path. This means that
#' the SparkDataFrame is searched by R when evaluating a variable, so columns in
#' the SparkDataFrame can be accessed by simply giving their names.
#'
#' @family SparkDataFrame functions
#' @rdname attach
#' @aliases attach attach,SparkDataFrame-method
#' @param what (SparkDataFrame) The SparkDataFrame to attach
#' @param pos (integer) Specify position in search() where to attach.
#' @param name (character) Name to use for the attached SparkDataFrame. Names
#' starting with package: are reserved for library.
#' @param warn.conflicts (logical) If TRUE, warnings are printed about conflicts
#' from attaching the database, unless that SparkDataFrame contains an object
#' @examples
#' \dontrun{
#' attach(irisDf)
#' summary(Sepal_Width)
#' }
#' @seealso \link{detach}
#' @note attach since 1.6.0
setMethod("attach",
signature(what = "SparkDataFrame"),
function(what, pos = 2L, name = deparse(substitute(what), backtick = FALSE),
warn.conflicts = TRUE) {
args <- as.list(environment()) # capture all parameters - this must be the first line
newEnv <- assignNewEnv(args$what)
args$what <- newEnv
do.call(attach, args)
})
#' Evaluate a R expression in an environment constructed from a SparkDataFrame
#'
#' Evaluate a R expression in an environment constructed from a SparkDataFrame
#' with() allows access to columns of a SparkDataFrame by simply referring to
#' their name. It appends every column of a SparkDataFrame into a new
#' environment. Then, the given expression is evaluated in this new
#' environment.
#'
#' @rdname with
#' @family SparkDataFrame functions
#' @aliases with,SparkDataFrame-method
#' @param data (SparkDataFrame) SparkDataFrame to use for constructing an environment.
#' @param expr (expression) Expression to evaluate.
#' @param ... arguments to be passed to future methods.
#' @examples
#' \dontrun{
#' with(irisDf, nrow(Sepal_Width))
#' }
#' @seealso \link{attach}
#' @note with since 1.6.0
setMethod("with",
signature(data = "SparkDataFrame"),
function(data, expr, ...) {
newEnv <- assignNewEnv(data)
eval(substitute(expr), envir = newEnv, enclos = newEnv)
})
#' Compactly display the structure of a dataset
#'
#' Display the structure of a SparkDataFrame, including column names, column types, as well as a
#' a small sample of rows.
#'
#' @name str
#' @rdname str
#' @aliases str,SparkDataFrame-method
#' @family SparkDataFrame functions
#' @param object a SparkDataFrame
#' @examples
#' \dontrun{
#' # Create a SparkDataFrame from the Iris dataset
#' irisDF <- createDataFrame(iris)
#'
#' # Show the structure of the SparkDataFrame
#' str(irisDF)
#' }
#' @note str since 1.6.1
setMethod("str",
signature(object = "SparkDataFrame"),
function(object) {
# TODO: These could be made global parameters, though in R it's not the case
MAX_CHAR_PER_ROW <- 120
MAX_COLS <- 100
# Get the column names and types of the DataFrame
names <- names(object)
types <- coltypes(object)
# Get the first elements of the dataset. Limit number of columns accordingly
localDF <- if (ncol(object) > MAX_COLS) {
head(object[, c(1:MAX_COLS)])
} else {
head(object)
}
# The number of observations will not be displayed as computing the
# number of rows is a very expensive operation
cat(paste0("'", class(object), "': ", length(names), " variables:\n"))
if (nrow(localDF) > 0) {
for (i in 1 : ncol(localDF)) {
# Get the first elements for each column
firstElements <- if (types[i] == "character") {
paste(paste0("\"", localDF[, i], "\""), collapse = " ")
} else {
paste(localDF[, i], collapse = " ")
}
# Add the corresponding number of spaces for alignment
spaces <- paste(rep(" ", max(nchar(names) - nchar(names[i]))), collapse = "")
# Get the short type. For 'character', it would be 'chr';
# 'for numeric', it's 'num', etc.
dataType <- SHORT_TYPES[[types[i]]]
if (is.null(dataType)) {
dataType <- substring(types[i], 1, 3)
}
# Concatenate the colnames, coltypes, and first
# elements of each column
line <- paste0(" $ ", names[i], spaces, ": ",
dataType, " ", firstElements)
# Chop off extra characters if this is too long
cat(substr(line, 1, MAX_CHAR_PER_ROW))
cat("\n")
}
if (ncol(localDF) < ncol(object)) {
cat(paste0("\nDisplaying first ", ncol(localDF), " columns only."))
}
}
})
#' drop
#'
#' Returns a new SparkDataFrame with columns dropped.
#' This is a no-op if schema doesn't contain column name(s).
#'
#' @param x a SparkDataFrame.
#' @param col a character vector of column names or a Column.
#' @param ... further arguments to be passed to or from other methods.
#' @return A SparkDataFrame.
#'
#' @family SparkDataFrame functions
#' @rdname drop
#' @name drop
#' @aliases drop,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' drop(df, "col1")
#' drop(df, c("col1", "col2"))
#' drop(df, df$col1)
#' }
#' @note drop since 2.0.0
setMethod("drop",
signature(x = "SparkDataFrame"),
function(x, col) {
stopifnot(class(col) == "character" || class(col) == "Column")
if (class(col) == "Column") {
sdf <- callJMethod(x@sdf, "drop", col@jc)
} else {
sdf <- callJMethod(x@sdf, "drop", as.list(col))
}
dataFrame(sdf)
})
# Expose base::drop
#' @name drop
#' @rdname drop
#' @aliases drop,ANY-method
#' @export
setMethod("drop",
signature(x = "ANY"),
function(x) {
base::drop(x)
})
#' Compute histogram statistics for given column
#'
#' This function computes a histogram for a given SparkR Column.
#'
#' @name histogram
#' @param nbins the number of bins (optional). Default value is 10.
#' @param col the column as Character string or a Column to build the histogram from.
#' @param df the SparkDataFrame containing the Column to build the histogram from.
#' @return a data.frame with the histogram statistics, i.e., counts and centroids.
#' @rdname histogram
#' @aliases histogram,SparkDataFrame,characterOrColumn-method
#' @family SparkDataFrame functions
#' @export
#' @examples
#' \dontrun{
#'
#' # Create a SparkDataFrame from the Iris dataset
#' irisDF <- createDataFrame(iris)
#'
#' # Compute histogram statistics
#' histStats <- histogram(irisDF, irisDF$Sepal_Length, nbins = 12)
#'
#' # Once SparkR has computed the histogram statistics, the histogram can be
#' # rendered using the ggplot2 library:
#'
#' require(ggplot2)
#' plot <- ggplot(histStats, aes(x = centroids, y = counts)) +
#' geom_bar(stat = "identity") +
#' xlab("Sepal_Length") + ylab("Frequency")
#' }
#' @note histogram since 2.0.0
setMethod("histogram",
signature(df = "SparkDataFrame", col = "characterOrColumn"),
function(df, col, nbins = 10) {
# Validate nbins
if (nbins < 2) {
stop("The number of bins must be a positive integer number greater than 1.")
}
# Round nbins to the smallest integer
nbins <- floor(nbins)
# Validate col
if (is.null(col)) {
stop("col must be specified.")
}
colname <- col
x <- if (class(col) == "character") {
if (!colname %in% names(df)) {
stop("Specified colname does not belong to the given SparkDataFrame.")
}
# Filter NA values in the target column and remove all other columns
df <- na.omit(df[, colname, drop = F])
getColumn(df, colname)
} else if (class(col) == "Column") {
# The given column needs to be appended to the SparkDataFrame so that we can
# use method describe() to compute statistics in one single pass. The new
# column must have a name that doesn't exist in the dataset.
# To do so, we generate a random column name with more characters than the
# longest colname in the dataset, but no more than 100 (think of a UUID).
# This column name will never be visible to the user, so the name is irrelevant.
# Limiting the colname length to 100 makes debugging easier and it does
# introduce a negligible probability of collision: assuming the user has 1 million
# columns AND all of them have names 100 characters long (which is very unlikely),
# AND they run 1 billion histograms, the probability of collision will roughly be
# 1 in 4.4 x 10 ^ 96
colname <- paste(base::sample(c(letters, LETTERS),
size = min(max(nchar(colnames(df))) + 1, 100),
replace = TRUE),
collapse = "")
# Append the given column to the dataset. This is to support Columns that
# don't belong to the SparkDataFrame but are rather expressions
df <- withColumn(df, colname, col)
# Filter NA values in the target column. Cannot remove all other columns
# since given Column may be an expression on one or more existing columns
df <- na.omit(df)
col
}
stats <- collect(describe(df[, colname, drop = F]))
min <- as.numeric(stats[4, 2])
max <- as.numeric(stats[5, 2])
# Normalize the data
xnorm <- (x - min) / (max - min)
# Round the data to 4 significant digits. This is to avoid rounding issues.
xnorm <- cast(xnorm * 10000, "integer") / 10000.0
# Since min = 0, max = 1 (data is already normalized)
normBinSize <- 1 / nbins
binsize <- (max - min) / nbins
approxBins <- xnorm / normBinSize
# Adjust values that are equal to the upper bound of each bin
bins <- cast(approxBins -
ifelse(approxBins == cast(approxBins, "integer") & x != min, 1, 0),
"integer")
df$bins <- bins
histStats <- collect(count(groupBy(df, "bins")))
names(histStats) <- c("bins", "counts")
# Fill bins with zero counts
y <- data.frame("bins" = seq(0, nbins - 1))
histStats <- merge(histStats, y, all.x = T, all.y = T)
histStats[is.na(histStats$count), 2] <- 0
# Compute centroids
histStats$centroids <- histStats$bins * binsize + min + binsize / 2
# Return the statistics
return(histStats)
})
#' Save the content of SparkDataFrame to an external database table via JDBC.
#'
#' Save the content of the SparkDataFrame to an external database table via JDBC. Additional JDBC
#' database connection properties can be set (...)
#'
#' Also, mode is used to specify the behavior of the save operation when
#' data already exists in the data source. There are four modes:
#' \itemize{
#' \item 'append': Contents of this SparkDataFrame are expected to be appended to existing data.
#' \item 'overwrite': Existing data is expected to be overwritten by the contents of this
#' SparkDataFrame.
#' \item 'error' or 'errorifexists': An exception is expected to be thrown.
#' \item 'ignore': The save operation is expected to not save the contents of the SparkDataFrame
#' and to not change the existing data.
#' }
#'
#' @param x a SparkDataFrame.
#' @param url JDBC database url of the form \code{jdbc:subprotocol:subname}.
#' @param tableName yhe name of the table in the external database.
#' @param mode one of 'append', 'overwrite', 'error', 'errorifexists', 'ignore'
#' save mode (it is 'error' by default)
#' @param ... additional JDBC database connection properties.
#' @family SparkDataFrame functions
#' @rdname write.jdbc
#' @name write.jdbc
#' @aliases write.jdbc,SparkDataFrame,character,character-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' jdbcUrl <- "jdbc:mysql://localhost:3306/databasename"
#' write.jdbc(df, jdbcUrl, "table", user = "username", password = "password")
#' }
#' @note write.jdbc since 2.0.0
setMethod("write.jdbc",
signature(x = "SparkDataFrame", url = "character", tableName = "character"),
function(x, url, tableName, mode = "error", ...) {
jprops <- varargsToJProperties(...)
write <- callJMethod(x@sdf, "write")
write <- setWriteMode(write, mode)
invisible(handledCallJMethod(write, "jdbc", url, tableName, jprops))
})
#' randomSplit
#'
#' Return a list of randomly split dataframes with the provided weights.
#'
#' @param x A SparkDataFrame
#' @param weights A vector of weights for splits, will be normalized if they don't sum to 1
#' @param seed A seed to use for random split
#'
#' @family SparkDataFrame functions
#' @aliases randomSplit,SparkDataFrame,numeric-method
#' @rdname randomSplit
#' @name randomSplit
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df <- createDataFrame(data.frame(id = 1:1000))
#' df_list <- randomSplit(df, c(2, 3, 5), 0)
#' # df_list contains 3 SparkDataFrames with each having about 200, 300 and 500 rows respectively
#' sapply(df_list, count)
#' }
#' @note randomSplit since 2.0.0
setMethod("randomSplit",
signature(x = "SparkDataFrame", weights = "numeric"),
function(x, weights, seed) {
if (!all(sapply(weights, function(c) { c >= 0 }))) {
stop("all weight values should not be negative")
}
normalized_list <- as.list(weights / sum(weights))
if (!missing(seed)) {
sdfs <- callJMethod(x@sdf, "randomSplit", normalized_list, as.integer(seed))
} else {
sdfs <- callJMethod(x@sdf, "randomSplit", normalized_list)
}
sapply(sdfs, dataFrame)
})
#' getNumPartitions
#'
#' Return the number of partitions
#'
#' @param x A SparkDataFrame
#' @family SparkDataFrame functions
#' @aliases getNumPartitions,SparkDataFrame-method
#' @rdname getNumPartitions
#' @name getNumPartitions
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df <- createDataFrame(cars, numPartitions = 2)
#' getNumPartitions(df)
#' }
#' @note getNumPartitions since 2.1.1
setMethod("getNumPartitions",
signature(x = "SparkDataFrame"),
function(x) {
callJMethod(callJMethod(x@sdf, "rdd"), "getNumPartitions")
})
#' isStreaming
#'
#' Returns TRUE if this SparkDataFrame contains one or more sources that continuously return data
#' as it arrives.
#'
#' @param x A SparkDataFrame
#' @return TRUE if this SparkDataFrame is from a streaming source
#' @family SparkDataFrame functions
#' @aliases isStreaming,SparkDataFrame-method
#' @rdname isStreaming
#' @name isStreaming
#' @seealso \link{read.stream} \link{write.stream}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df <- read.stream("socket", host = "localhost", port = 9999)
#' isStreaming(df)
#' }
#' @note isStreaming since 2.2.0
#' @note experimental
setMethod("isStreaming",
signature(x = "SparkDataFrame"),
function(x) {
callJMethod(x@sdf, "isStreaming")
})
#' Write the streaming SparkDataFrame to a data source.
#'
#' The data source is specified by the \code{source} and a set of options (...).
#' If \code{source} is not specified, the default data source configured by
#' spark.sql.sources.default will be used.
#'
#' Additionally, \code{outputMode} specifies how data of a streaming SparkDataFrame is written to a
#' output data source. There are three modes:
#' \itemize{
#' \item append: Only the new rows in the streaming SparkDataFrame will be written out. This
#' output mode can be only be used in queries that do not contain any aggregation.
#' \item complete: All the rows in the streaming SparkDataFrame will be written out every time
#' there are some updates. This output mode can only be used in queries that
#' contain aggregations.
#' \item update: Only the rows that were updated in the streaming SparkDataFrame will be written
#' out every time there are some updates. If the query doesn't contain aggregations,
#' it will be equivalent to \code{append} mode.
#' }
#'
#' @param df a streaming SparkDataFrame.
#' @param source a name for external data source.
#' @param outputMode one of 'append', 'complete', 'update'.
#' @param ... additional argument(s) passed to the method.
#'
#' @family SparkDataFrame functions
#' @seealso \link{read.stream}
#' @aliases write.stream,SparkDataFrame-method
#' @rdname write.stream
#' @name write.stream
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df <- read.stream("socket", host = "localhost", port = 9999)
#' isStreaming(df)
#' wordCounts <- count(group_by(df, "value"))
#'
#' # console
#' q <- write.stream(wordCounts, "console", outputMode = "complete")
#' # text stream
#' q <- write.stream(df, "text", path = "/home/user/out", checkpointLocation = "/home/user/cp")
#' # memory stream
#' q <- write.stream(wordCounts, "memory", queryName = "outs", outputMode = "complete")
#' head(sql("SELECT * from outs"))
#' queryName(q)
#'
#' stopQuery(q)
#' }
#' @note write.stream since 2.2.0
#' @note experimental
setMethod("write.stream",
signature(df = "SparkDataFrame"),
function(df, source = NULL, outputMode = NULL, ...) {
if (!is.null(source) && !is.character(source)) {
stop("source should be character, NULL or omitted. It is the data source specified ",
"in 'spark.sql.sources.default' configuration by default.")
}
if (!is.null(outputMode) && !is.character(outputMode)) {
stop("outputMode should be character or omitted.")
}
if (is.null(source)) {
source <- getDefaultSqlSource()
}
options <- varargsToStrEnv(...)
write <- handledCallJMethod(df@sdf, "writeStream")
write <- callJMethod(write, "format", source)
if (!is.null(outputMode)) {
write <- callJMethod(write, "outputMode", outputMode)
}
write <- callJMethod(write, "options", options)
ssq <- handledCallJMethod(write, "start")
streamingQuery(ssq)
})
#' checkpoint
#'
#' Returns a checkpointed version of this SparkDataFrame. Checkpointing can be used to truncate the
#' logical plan, which is especially useful in iterative algorithms where the plan may grow
#' exponentially. It will be saved to files inside the checkpoint directory set with
#' \code{setCheckpointDir}
#'
#' @param x A SparkDataFrame
#' @param eager whether to checkpoint this SparkDataFrame immediately
#' @return a new checkpointed SparkDataFrame
#' @family SparkDataFrame functions
#' @aliases checkpoint,SparkDataFrame-method
#' @rdname checkpoint
#' @name checkpoint
#' @seealso \link{setCheckpointDir}
#' @export
#' @examples
#'\dontrun{
#' setCheckpointDir("/checkpoint")
#' df <- checkpoint(df)
#' }
#' @note checkpoint since 2.2.0
setMethod("checkpoint",
signature(x = "SparkDataFrame"),
function(x, eager = TRUE) {
df <- callJMethod(x@sdf, "checkpoint", as.logical(eager))
dataFrame(df)
})
#' cube
#'
#' Create a multi-dimensional cube for the SparkDataFrame using the specified columns.
#'
#' If grouping expression is missing \code{cube} creates a single global aggregate and is
#' equivalent to direct application of \link{agg}.
#'
#' @param x a SparkDataFrame.
#' @param ... character name(s) or Column(s) to group on.
#' @return A GroupedData.
#' @family SparkDataFrame functions
#' @aliases cube,SparkDataFrame-method
#' @rdname cube
#' @name cube
#' @export
#' @examples
#' \dontrun{
#' df <- createDataFrame(mtcars)
#' mean(cube(df, "cyl", "gear", "am"), "mpg")
#'
#' # Following calls are equivalent
#' agg(cube(df), mean(df$mpg))
#' agg(df, mean(df$mpg))
#' }
#' @note cube since 2.3.0
#' @seealso \link{agg}, \link{groupBy}, \link{rollup}
setMethod("cube",
signature(x = "SparkDataFrame"),
function(x, ...) {
cols <- list(...)
jcol <- lapply(cols, function(x) if (class(x) == "Column") x@jc else column(x)@jc)
sgd <- callJMethod(x@sdf, "cube", jcol)
groupedData(sgd)
})
#' rollup
#'
#' Create a multi-dimensional rollup for the SparkDataFrame using the specified columns.
#'
#' If grouping expression is missing \code{rollup} creates a single global aggregate and is
#' equivalent to direct application of \link{agg}.
#'
#' @param x a SparkDataFrame.
#' @param ... character name(s) or Column(s) to group on.
#' @return A GroupedData.
#' @family SparkDataFrame functions
#' @aliases rollup,SparkDataFrame-method
#' @rdname rollup
#' @name rollup
#' @export
#' @examples
#'\dontrun{
#' df <- createDataFrame(mtcars)
#' mean(rollup(df, "cyl", "gear", "am"), "mpg")
#'
#' # Following calls are equivalent
#' agg(rollup(df), mean(df$mpg))
#' agg(df, mean(df$mpg))
#' }
#' @note rollup since 2.3.0
#' @seealso \link{agg}, \link{cube}, \link{groupBy}
setMethod("rollup",
signature(x = "SparkDataFrame"),
function(x, ...) {
cols <- list(...)
jcol <- lapply(cols, function(x) if (class(x) == "Column") x@jc else column(x)@jc)
sgd <- callJMethod(x@sdf, "rollup", jcol)
groupedData(sgd)
})
#' hint
#'
#' Specifies execution plan hint and return a new SparkDataFrame.
#'
#' @param x a SparkDataFrame.
#' @param name a name of the hint.
#' @param ... optional parameters for the hint.
#' @return A SparkDataFrame.
#' @family SparkDataFrame functions
#' @aliases hint,SparkDataFrame,character-method
#' @rdname hint
#' @name hint
#' @export
#' @examples
#' \dontrun{
#' df <- createDataFrame(mtcars)
#' avg_mpg <- mean(groupBy(createDataFrame(mtcars), "cyl"), "mpg")
#'
#' head(join(df, hint(avg_mpg, "broadcast"), df$cyl == avg_mpg$cyl))
#' }
#' @note hint since 2.2.0
setMethod("hint",
signature(x = "SparkDataFrame", name = "character"),
function(x, name, ...) {
parameters <- list(...)
stopifnot(all(sapply(parameters, is.character)))
jdf <- callJMethod(x@sdf, "hint", name, parameters)
dataFrame(jdf)
})
#' alias
#'
#' @aliases alias,SparkDataFrame-method
#' @family SparkDataFrame functions
#' @rdname alias
#' @name alias
#' @export
#' @examples
#' \dontrun{
#' df <- alias(createDataFrame(mtcars), "mtcars")
#' avg_mpg <- alias(agg(groupBy(df, df$cyl), avg(df$mpg)), "avg_mpg")
#'
#' head(select(df, column("mtcars.mpg")))
#' head(join(df, avg_mpg, column("mtcars.cyl") == column("avg_mpg.cyl")))
#' }
#' @note alias(SparkDataFrame) since 2.3.0
setMethod("alias",
signature(object = "SparkDataFrame"),
function(object, data) {
stopifnot(is.character(data))
sdf <- callJMethod(object@sdf, "alias", data)
dataFrame(sdf)
})
#' broadcast
#'
#' Return a new SparkDataFrame marked as small enough for use in broadcast joins.
#'
#' Equivalent to \code{hint(x, "broadcast")}.
#'
#' @param x a SparkDataFrame.
#' @return a SparkDataFrame.
#'
#' @aliases broadcast,SparkDataFrame-method
#' @family SparkDataFrame functions
#' @rdname broadcast
#' @name broadcast
#' @export
#' @examples
#' \dontrun{
#' df <- createDataFrame(mtcars)
#' avg_mpg <- mean(groupBy(createDataFrame(mtcars), "cyl"), "mpg")
#'
#' head(join(df, broadcast(avg_mpg), df$cyl == avg_mpg$cyl))
#' }
#' @note broadcast since 2.3.0
setMethod("broadcast",
signature(x = "SparkDataFrame"),
function(x) {
sdf <- callJStatic("org.apache.spark.sql.functions", "broadcast", x@sdf)
dataFrame(sdf)
})
vkapartzianis/SparkR documentation built on May 18, 2019, 8:10 p.m.
R Package Documentation
Browse R Packages
We want your feedback!
Note that we can't provide technical support on individual packages. You should contact the package authors for that.
#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# DataFrame.R - SparkDataFrame class and methods implemented in S4 OO classes
#' @include generics.R jobj.R schema.R RDD.R pairRDD.R column.R group.R
NULL
setOldClass("jobj")
setOldClass("structType")
#' S4 class that represents a SparkDataFrame
#'
#' SparkDataFrames can be created using functions like \link{createDataFrame},
#' \link{read.json}, \link{table} etc.
#'
#' @family SparkDataFrame functions
#' @rdname SparkDataFrame
#' @docType class
#'
#' @slot env An R environment that stores bookkeeping states of the SparkDataFrame
#' @slot sdf A Java object reference to the backing Scala DataFrame
#' @seealso \link{createDataFrame}, \link{read.json}, \link{table}
#' @seealso \url{https://spark.apache.org/docs/latest/sparkr.html#sparkr-dataframes}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df <- createDataFrame(faithful)
#'}
#' @note SparkDataFrame since 2.0.0
setClass("SparkDataFrame",
slots = list(env = "environment",
sdf = "jobj"))
setMethod("initialize", "SparkDataFrame", function(.Object, sdf, isCached) {
.Object@env <- new.env()
.Object@env$isCached <- isCached
.Object@sdf <- sdf
.Object
})
#' Set options/mode and then return the write object
#' @noRd
setWriteOptions <- function(write, path = NULL, mode = "error", ...) {
options <- varargsToStrEnv(...)
if (!is.null(path)) {
options[["path"]] <- path
}
write <- setWriteMode(write, mode)
write <- callJMethod(write, "options", options)
write
}
#' Set mode and then return the write object
#' @noRd
setWriteMode <- function(write, mode) {
if (!is.character(mode)) {
stop("mode should be character or omitted. It is 'error' by default.")
}
write <- handledCallJMethod(write, "mode", mode)
write
}
#' @export
#' @param sdf A Java object reference to the backing Scala DataFrame
#' @param isCached TRUE if the SparkDataFrame is cached
#' @noRd
dataFrame <- function(sdf, isCached = FALSE) {
new("SparkDataFrame", sdf, isCached)
}
############################ SparkDataFrame Methods ##############################################
#' Print Schema of a SparkDataFrame
#'
#' Prints out the schema in tree format
#'
#' @param x A SparkDataFrame
#'
#' @family SparkDataFrame functions
#' @rdname printSchema
#' @name printSchema
#' @aliases printSchema,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' printSchema(df)
#'}
#' @note printSchema since 1.4.0
setMethod("printSchema",
signature(x = "SparkDataFrame"),
function(x) {
schemaString <- callJMethod(schema(x)$jobj, "treeString")
cat(schemaString)
})
#' Get schema object
#'
#' Returns the schema of this SparkDataFrame as a structType object.
#'
#' @param x A SparkDataFrame
#'
#' @family SparkDataFrame functions
#' @rdname schema
#' @name schema
#' @aliases schema,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' dfSchema <- schema(df)
#'}
#' @note schema since 1.4.0
setMethod("schema",
signature(x = "SparkDataFrame"),
function(x) {
structType(callJMethod(x@sdf, "schema"))
})
#' Explain
#'
#' Print the logical and physical Catalyst plans to the console for debugging.
#'
#' @family SparkDataFrame functions
#' @aliases explain,SparkDataFrame-method
#' @rdname explain
#' @name explain
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' explain(df, TRUE)
#'}
#' @note explain since 1.4.0
setMethod("explain",
signature(x = "SparkDataFrame"),
function(x, extended = FALSE) {
queryExec <- callJMethod(x@sdf, "queryExecution")
if (extended) {
cat(callJMethod(queryExec, "toString"))
} else {
execPlan <- callJMethod(queryExec, "executedPlan")
cat(callJMethod(execPlan, "toString"))
}
})
#' isLocal
#'
#' Returns True if the \code{collect} and \code{take} methods can be run locally
#' (without any Spark executors).
#'
#' @param x A SparkDataFrame
#'
#' @family SparkDataFrame functions
#' @rdname isLocal
#' @name isLocal
#' @aliases isLocal,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' isLocal(df)
#'}
#' @note isLocal since 1.4.0
setMethod("isLocal",
signature(x = "SparkDataFrame"),
function(x) {
callJMethod(x@sdf, "isLocal")
})
#' showDF
#'
#' Print the first numRows rows of a SparkDataFrame
#'
#' @param x a SparkDataFrame.
#' @param numRows the number of rows to print. Defaults to 20.
#' @param truncate whether truncate long strings. If \code{TRUE}, strings more than
#' 20 characters will be truncated. However, if set greater than zero,
#' truncates strings longer than \code{truncate} characters and all cells
#' will be aligned right.
#' @param vertical whether print output rows vertically (one line per column value).
#' @param ... further arguments to be passed to or from other methods.
#' @family SparkDataFrame functions
#' @aliases showDF,SparkDataFrame-method
#' @rdname showDF
#' @name showDF
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' showDF(df)
#'}
#' @note showDF since 1.4.0
setMethod("showDF",
signature(x = "SparkDataFrame"),
function(x, numRows = 20, truncate = TRUE, vertical = FALSE) {
if (is.logical(truncate) && truncate) {
s <- callJMethod(x@sdf, "showString", numToInt(numRows), numToInt(20), vertical)
} else {
truncate2 <- as.numeric(truncate)
s <- callJMethod(x@sdf, "showString", numToInt(numRows), numToInt(truncate2),
vertical)
}
cat(s)
})
#' show
#'
#' Print class and type information of a Spark object.
#'
#' @param object a Spark object. Can be a SparkDataFrame, Column, GroupedData, WindowSpec.
#'
#' @family SparkDataFrame functions
#' @rdname show
#' @aliases show,SparkDataFrame-method
#' @name show
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' show(df)
#'}
#' @note show(SparkDataFrame) since 1.4.0
setMethod("show", "SparkDataFrame",
function(object) {
cols <- lapply(dtypes(object), function(l) {
paste(l, collapse = ":")
})
s <- paste(cols, collapse = ", ")
cat(paste(class(object), "[", s, "]\n", sep = ""))
})
#' DataTypes
#'
#' Return all column names and their data types as a list
#'
#' @param x A SparkDataFrame
#'
#' @family SparkDataFrame functions
#' @rdname dtypes
#' @name dtypes
#' @aliases dtypes,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' dtypes(df)
#'}
#' @note dtypes since 1.4.0
setMethod("dtypes",
signature(x = "SparkDataFrame"),
function(x) {
lapply(schema(x)$fields(), function(f) {
c(f$name(), f$dataType.simpleString())
})
})
#' Column Names of SparkDataFrame
#'
#' Return a vector of column names.
#'
#' @param x a SparkDataFrame.
#'
#' @family SparkDataFrame functions
#' @rdname columns
#' @name columns
#' @aliases columns,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' columns(df)
#' colnames(df)
#'}
#' @note columns since 1.4.0
setMethod("columns",
signature(x = "SparkDataFrame"),
function(x) {
sapply(schema(x)$fields(), function(f) {
f$name()
})
})
#' @rdname columns
#' @name names
#' @aliases names,SparkDataFrame-method
#' @note names since 1.5.0
setMethod("names",
signature(x = "SparkDataFrame"),
function(x) {
columns(x)
})
#' @rdname columns
#' @aliases names<-,SparkDataFrame-method
#' @name names<-
#' @note names<- since 1.5.0
setMethod("names<-",
signature(x = "SparkDataFrame"),
function(x, value) {
colnames(x) <- value
x
})
#' @rdname columns
#' @aliases colnames,SparkDataFrame-method
#' @name colnames
#' @note colnames since 1.6.0
setMethod("colnames",
signature(x = "SparkDataFrame"),
function(x) {
columns(x)
})
#' @param value a character vector. Must have the same length as the number
#' of columns to be renamed.
#' @rdname columns
#' @aliases colnames<-,SparkDataFrame-method
#' @name colnames<-
#' @note colnames<- since 1.6.0
setMethod("colnames<-",
signature(x = "SparkDataFrame"),
function(x, value) {
# Check parameter integrity
if (class(value) != "character") {
stop("Invalid column names.")
}
if (length(value) != ncol(x)) {
stop(
"Column names must have the same length as the number of columns in the dataset.")
}
if (any(is.na(value))) {
stop("Column names cannot be NA.")
}
# Check if the column names have . in it
if (any(regexec(".", value, fixed = TRUE)[[1]][1] != -1)) {
stop("Column names cannot contain the '.' symbol.")
}
sdf <- callJMethod(x@sdf, "toDF", as.list(value))
dataFrame(sdf)
})
#' coltypes
#'
#' Get column types of a SparkDataFrame
#'
#' @param x A SparkDataFrame
#' @return value A character vector with the column types of the given SparkDataFrame
#' @rdname coltypes
#' @aliases coltypes,SparkDataFrame-method
#' @name coltypes
#' @family SparkDataFrame functions
#' @export
#' @examples
#'\dontrun{
#' irisDF <- createDataFrame(iris)
#' coltypes(irisDF) # get column types
#'}
#' @note coltypes since 1.6.0
setMethod("coltypes",
signature(x = "SparkDataFrame"),
function(x) {
# Get the data types of the SparkDataFrame by invoking dtypes() function
types <- sapply(dtypes(x), function(x) {x[[2]]})
# Map Spark data types into R's data types using DATA_TYPES environment
rTypes <- sapply(types, USE.NAMES = F, FUN = function(x) {
# Check for primitive types
type <- PRIMITIVE_TYPES[[x]]
if (is.null(type)) {
# Check for complex types
for (t in names(COMPLEX_TYPES)) {
if (substring(x, 1, nchar(t)) == t) {
type <- COMPLEX_TYPES[[t]]
break
}
}
if (is.null(type)) {
specialtype <- specialtypeshandle(x)
if (is.null(specialtype)) {
stop(paste("Unsupported data type: ", x))
}
type <- PRIMITIVE_TYPES[[specialtype]]
}
}
type[[1]]
})
# Find which types don't have mapping to R
naIndices <- which(is.na(rTypes))
# Assign the original scala data types to the unmatched ones
rTypes[naIndices] <- types[naIndices]
rTypes
})
#' coltypes
#'
#' Set the column types of a SparkDataFrame.
#'
#' @param value A character vector with the target column types for the given
#' SparkDataFrame. Column types can be one of integer, numeric/double, character, logical, or NA
#' to keep that column as-is.
#' @rdname coltypes
#' @name coltypes<-
#' @aliases coltypes<-,SparkDataFrame,character-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' coltypes(df) <- c("character", "integer") # set column types
#' coltypes(df) <- c(NA, "numeric") # set column types
#'}
#' @note coltypes<- since 1.6.0
setMethod("coltypes<-",
signature(x = "SparkDataFrame", value = "character"),
function(x, value) {
cols <- columns(x)
ncols <- length(cols)
if (length(value) == 0) {
stop("Cannot set types of an empty SparkDataFrame with no Column")
}
if (length(value) != ncols) {
stop("Length of type vector should match the number of columns for SparkDataFrame")
}
newCols <- lapply(seq_len(ncols), function(i) {
col <- getColumn(x, cols[i])
if (!is.na(value[i])) {
stype <- rToSQLTypes[[value[i]]]
if (is.null(stype)) {
stop("Only atomic type is supported for column types")
}
cast(col, stype)
} else {
col
}
})
nx <- select(x, newCols)
dataFrame(nx@sdf)
})
#' Creates a temporary view using the given name.
#'
#' Creates a new temporary view using a SparkDataFrame in the Spark Session. If a
#' temporary view with the same name already exists, replaces it.
#'
#' @param x A SparkDataFrame
#' @param viewName A character vector containing the name of the table
#'
#' @family SparkDataFrame functions
#' @rdname createOrReplaceTempView
#' @name createOrReplaceTempView
#' @aliases createOrReplaceTempView,SparkDataFrame,character-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' createOrReplaceTempView(df, "json_df")
#' new_df <- sql("SELECT * FROM json_df")
#'}
#' @note createOrReplaceTempView since 2.0.0
setMethod("createOrReplaceTempView",
signature(x = "SparkDataFrame", viewName = "character"),
function(x, viewName) {
invisible(callJMethod(x@sdf, "createOrReplaceTempView", viewName))
})
#' (Deprecated) Register Temporary Table
#'
#' Registers a SparkDataFrame as a Temporary Table in the SparkSession
#' @param x A SparkDataFrame
#' @param tableName A character vector containing the name of the table
#'
#' @family SparkDataFrame functions
#' @seealso \link{createOrReplaceTempView}
#' @rdname registerTempTable-deprecated
#' @name registerTempTable
#' @aliases registerTempTable,SparkDataFrame,character-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' registerTempTable(df, "json_df")
#' new_df <- sql("SELECT * FROM json_df")
#'}
#' @note registerTempTable since 1.4.0
setMethod("registerTempTable",
signature(x = "SparkDataFrame", tableName = "character"),
function(x, tableName) {
.Deprecated("createOrReplaceTempView")
invisible(callJMethod(x@sdf, "createOrReplaceTempView", tableName))
})
#' insertInto
#'
#' Insert the contents of a SparkDataFrame into a table registered in the current SparkSession.
#'
#' @param x a SparkDataFrame.
#' @param tableName a character vector containing the name of the table.
#' @param overwrite a logical argument indicating whether or not to overwrite.
#' @param ... further arguments to be passed to or from other methods.
#' the existing rows in the table.
#'
#' @family SparkDataFrame functions
#' @rdname insertInto
#' @name insertInto
#' @aliases insertInto,SparkDataFrame,character-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df <- read.df(path, "parquet")
#' df2 <- read.df(path2, "parquet")
#' saveAsTable(df, "table1")
#' insertInto(df2, "table1", overwrite = TRUE)
#'}
#' @note insertInto since 1.4.0
setMethod("insertInto",
signature(x = "SparkDataFrame", tableName = "character"),
function(x, tableName, overwrite = FALSE) {
write <- callJMethod(x@sdf, "write")
write <- setWriteMode(write, ifelse(overwrite, "overwrite", "append"))
invisible(callJMethod(write, "insertInto", tableName))
})
#' Cache
#'
#' Persist with the default storage level (MEMORY_ONLY).
#'
#' @param x A SparkDataFrame
#'
#' @family SparkDataFrame functions
#' @aliases cache,SparkDataFrame-method
#' @rdname cache
#' @name cache
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' cache(df)
#'}
#' @note cache since 1.4.0
setMethod("cache",
signature(x = "SparkDataFrame"),
function(x) {
cached <- callJMethod(x@sdf, "cache")
x@env$isCached <- TRUE
x
})
#' Persist
#'
#' Persist this SparkDataFrame with the specified storage level. For details of the
#' supported storage levels, refer to
#' \url{http://spark.apache.org/docs/latest/rdd-programming-guide.html#rdd-persistence}.
#'
#' @param x the SparkDataFrame to persist.
#' @param newLevel storage level chosen for the persistance. See available options in
#' the description.
#'
#' @family SparkDataFrame functions
#' @rdname persist
#' @name persist
#' @aliases persist,SparkDataFrame,character-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' persist(df, "MEMORY_AND_DISK")
#'}
#' @note persist since 1.4.0
setMethod("persist",
signature(x = "SparkDataFrame", newLevel = "character"),
function(x, newLevel) {
callJMethod(x@sdf, "persist", getStorageLevel(newLevel))
x@env$isCached <- TRUE
x
})
#' Unpersist
#'
#' Mark this SparkDataFrame as non-persistent, and remove all blocks for it from memory and
#' disk.
#'
#' @param x the SparkDataFrame to unpersist.
#' @param blocking whether to block until all blocks are deleted.
#' @param ... further arguments to be passed to or from other methods.
#'
#' @family SparkDataFrame functions
#' @rdname unpersist
#' @aliases unpersist,SparkDataFrame-method
#' @name unpersist
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' persist(df, "MEMORY_AND_DISK")
#' unpersist(df)
#'}
#' @note unpersist since 1.4.0
setMethod("unpersist",
signature(x = "SparkDataFrame"),
function(x, blocking = TRUE) {
callJMethod(x@sdf, "unpersist", blocking)
x@env$isCached <- FALSE
x
})
#' StorageLevel
#'
#' Get storagelevel of this SparkDataFrame.
#'
#' @param x the SparkDataFrame to get the storageLevel.
#'
#' @family SparkDataFrame functions
#' @rdname storageLevel
#' @aliases storageLevel,SparkDataFrame-method
#' @name storageLevel
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' persist(df, "MEMORY_AND_DISK")
#' storageLevel(df)
#'}
#' @note storageLevel since 2.1.0
setMethod("storageLevel",
signature(x = "SparkDataFrame"),
function(x) {
storageLevelToString(callJMethod(x@sdf, "storageLevel"))
})
#' Coalesce
#'
#' Returns a new SparkDataFrame that has exactly \code{numPartitions} partitions.
#' This operation results in a narrow dependency, e.g. if you go from 1000 partitions to 100
#' partitions, there will not be a shuffle, instead each of the 100 new partitions will claim 10 of
#' the current partitions. If a larger number of partitions is requested, it will stay at the
#' current number of partitions.
#'
#' However, if you're doing a drastic coalesce on a SparkDataFrame, e.g. to numPartitions = 1,
#' this may result in your computation taking place on fewer nodes than
#' you like (e.g. one node in the case of numPartitions = 1). To avoid this,
#' call \code{repartition}. This will add a shuffle step, but means the
#' current upstream partitions will be executed in parallel (per whatever
#' the current partitioning is).
#'
#' @param numPartitions the number of partitions to use.
#'
#' @family SparkDataFrame functions
#' @rdname coalesce
#' @name coalesce
#' @aliases coalesce,SparkDataFrame-method
#' @seealso \link{repartition}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' newDF <- coalesce(df, 1L)
#'}
#' @note coalesce(SparkDataFrame) since 2.1.1
setMethod("coalesce",
signature(x = "SparkDataFrame"),
function(x, numPartitions) {
stopifnot(is.numeric(numPartitions))
sdf <- callJMethod(x@sdf, "coalesce", numToInt(numPartitions))
dataFrame(sdf)
})
#' Repartition
#'
#' The following options for repartition are possible:
#' \itemize{
#' \item{1.} {Return a new SparkDataFrame that has exactly \code{numPartitions}.}
#' \item{2.} {Return a new SparkDataFrame hash partitioned by
#' the given columns into \code{numPartitions}.}
#' \item{3.} {Return a new SparkDataFrame hash partitioned by the given column(s),
#' using \code{spark.sql.shuffle.partitions} as number of partitions.}
#'}
#' @param x a SparkDataFrame.
#' @param numPartitions the number of partitions to use.
#' @param col the column by which the partitioning will be performed.
#' @param ... additional column(s) to be used in the partitioning.
#'
#' @family SparkDataFrame functions
#' @rdname repartition
#' @name repartition
#' @aliases repartition,SparkDataFrame-method
#' @seealso \link{coalesce}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' newDF <- repartition(df, 2L)
#' newDF <- repartition(df, numPartitions = 2L)
#' newDF <- repartition(df, col = df$"col1", df$"col2")
#' newDF <- repartition(df, 3L, col = df$"col1", df$"col2")
#'}
#' @note repartition since 1.4.0
setMethod("repartition",
signature(x = "SparkDataFrame"),
function(x, numPartitions = NULL, col = NULL, ...) {
if (!is.null(numPartitions) && is.numeric(numPartitions)) {
# number of partitions and columns both are specified
if (!is.null(col) && class(col) == "Column") {
cols <- list(col, ...)
jcol <- lapply(cols, function(c) { c@jc })
sdf <- callJMethod(x@sdf, "repartition", numToInt(numPartitions), jcol)
} else {
# only number of partitions is specified
sdf <- callJMethod(x@sdf, "repartition", numToInt(numPartitions))
}
} else if (!is.null(col) && class(col) == "Column") {
# only columns are specified
cols <- list(col, ...)
jcol <- lapply(cols, function(c) { c@jc })
sdf <- callJMethod(x@sdf, "repartition", jcol)
} else {
stop("Please, specify the number of partitions and/or a column(s)")
}
dataFrame(sdf)
})
#' toJSON
#'
#' Converts a SparkDataFrame into a SparkDataFrame of JSON string.
#'
#' Each row is turned into a JSON document with columns as different fields.
#' The returned SparkDataFrame has a single character column with the name \code{value}
#'
#' @param x a SparkDataFrame
#' @return a SparkDataFrame
#' @family SparkDataFrame functions
#' @rdname toJSON
#' @name toJSON
#' @aliases toJSON,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.parquet"
#' df <- read.parquet(path)
#' df_json <- toJSON(df)
#'}
#' @note toJSON since 2.2.0
setMethod("toJSON",
signature(x = "SparkDataFrame"),
function(x) {
jsonDS <- callJMethod(x@sdf, "toJSON")
df <- callJMethod(jsonDS, "toDF")
dataFrame(df)
})
#' Save the contents of SparkDataFrame as a JSON file
#'
#' Save the contents of a SparkDataFrame as a JSON file (\href{http://jsonlines.org/}{
#' JSON Lines text format or newline-delimited JSON}). Files written out
#' with this method can be read back in as a SparkDataFrame using read.json().
#'
#' @param x A SparkDataFrame
#' @param path The directory where the file is saved
#' @param mode one of 'append', 'overwrite', 'error', 'errorifexists', 'ignore'
#' save mode (it is 'error' by default)
#' @param ... additional argument(s) passed to the method.
#'
#' @family SparkDataFrame functions
#' @rdname write.json
#' @name write.json
#' @aliases write.json,SparkDataFrame,character-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' write.json(df, "/tmp/sparkr-tmp/")
#'}
#' @note write.json since 1.6.0
setMethod("write.json",
signature(x = "SparkDataFrame", path = "character"),
function(x, path, mode = "error", ...) {
write <- callJMethod(x@sdf, "write")
write <- setWriteOptions(write, mode = mode, ...)
invisible(handledCallJMethod(write, "json", path))
})
#' Save the contents of SparkDataFrame as an ORC file, preserving the schema.
#'
#' Save the contents of a SparkDataFrame as an ORC file, preserving the schema. Files written out
#' with this method can be read back in as a SparkDataFrame using read.orc().
#'
#' @param x A SparkDataFrame
#' @param path The directory where the file is saved
#' @param mode one of 'append', 'overwrite', 'error', 'errorifexists', 'ignore'
#' save mode (it is 'error' by default)
#' @param ... additional argument(s) passed to the method.
#'
#' @family SparkDataFrame functions
#' @aliases write.orc,SparkDataFrame,character-method
#' @rdname write.orc
#' @name write.orc
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' write.orc(df, "/tmp/sparkr-tmp1/")
#' }
#' @note write.orc since 2.0.0
setMethod("write.orc",
signature(x = "SparkDataFrame", path = "character"),
function(x, path, mode = "error", ...) {
write <- callJMethod(x@sdf, "write")
write <- setWriteOptions(write, mode = mode, ...)
invisible(handledCallJMethod(write, "orc", path))
})
#' Save the contents of SparkDataFrame as a Parquet file, preserving the schema.
#'
#' Save the contents of a SparkDataFrame as a Parquet file, preserving the schema. Files written out
#' with this method can be read back in as a SparkDataFrame using read.parquet().
#'
#' @param x A SparkDataFrame
#' @param path The directory where the file is saved
#' @param mode one of 'append', 'overwrite', 'error', 'errorifexists', 'ignore'
#' save mode (it is 'error' by default)
#' @param ... additional argument(s) passed to the method.
#'
#' @family SparkDataFrame functions
#' @rdname write.parquet
#' @name write.parquet
#' @aliases write.parquet,SparkDataFrame,character-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' write.parquet(df, "/tmp/sparkr-tmp1/")
#' saveAsParquetFile(df, "/tmp/sparkr-tmp2/")
#'}
#' @note write.parquet since 1.6.0
setMethod("write.parquet",
signature(x = "SparkDataFrame", path = "character"),
function(x, path, mode = "error", ...) {
write <- callJMethod(x@sdf, "write")
write <- setWriteOptions(write, mode = mode, ...)
invisible(handledCallJMethod(write, "parquet", path))
})
#' @rdname write.parquet
#' @name saveAsParquetFile
#' @aliases saveAsParquetFile,SparkDataFrame,character-method
#' @export
#' @note saveAsParquetFile since 1.4.0
setMethod("saveAsParquetFile",
signature(x = "SparkDataFrame", path = "character"),
function(x, path) {
.Deprecated("write.parquet")
write.parquet(x, path)
})
#' Save the content of SparkDataFrame in a text file at the specified path.
#'
#' Save the content of the SparkDataFrame in a text file at the specified path.
#' The SparkDataFrame must have only one column of string type with the name "value".
#' Each row becomes a new line in the output file.
#'
#' @param x A SparkDataFrame
#' @param path The directory where the file is saved
#' @param mode one of 'append', 'overwrite', 'error', 'errorifexists', 'ignore'
#' save mode (it is 'error' by default)
#' @param ... additional argument(s) passed to the method.
#'
#' @family SparkDataFrame functions
#' @aliases write.text,SparkDataFrame,character-method
#' @rdname write.text
#' @name write.text
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.txt"
#' df <- read.text(path)
#' write.text(df, "/tmp/sparkr-tmp/")
#'}
#' @note write.text since 2.0.0
setMethod("write.text",
signature(x = "SparkDataFrame", path = "character"),
function(x, path, mode = "error", ...) {
write <- callJMethod(x@sdf, "write")
write <- setWriteOptions(write, mode = mode, ...)
invisible(handledCallJMethod(write, "text", path))
})
#' Distinct
#'
#' Return a new SparkDataFrame containing the distinct rows in this SparkDataFrame.
#'
#' @param x A SparkDataFrame
#'
#' @family SparkDataFrame functions
#' @aliases distinct,SparkDataFrame-method
#' @rdname distinct
#' @name distinct
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' distinctDF <- distinct(df)
#'}
#' @note distinct since 1.4.0
setMethod("distinct",
signature(x = "SparkDataFrame"),
function(x) {
sdf <- callJMethod(x@sdf, "distinct")
dataFrame(sdf)
})
#' @rdname distinct
#' @name unique
#' @aliases unique,SparkDataFrame-method
#' @note unique since 1.5.0
setMethod("unique",
signature(x = "SparkDataFrame"),
function(x) {
distinct(x)
})
#' Sample
#'
#' Return a sampled subset of this SparkDataFrame using a random seed.
#' Note: this is not guaranteed to provide exactly the fraction specified
#' of the total count of of the given SparkDataFrame.
#'
#' @param x A SparkDataFrame
#' @param withReplacement Sampling with replacement or not
#' @param fraction The (rough) sample target fraction
#' @param seed Randomness seed value. Default is a random seed.
#'
#' @family SparkDataFrame functions
#' @aliases sample,SparkDataFrame-method
#' @rdname sample
#' @name sample
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' collect(sample(df, fraction = 0.5))
#' collect(sample(df, FALSE, 0.5))
#' collect(sample(df, TRUE, 0.5, seed = 3))
#'}
#' @note sample since 1.4.0
setMethod("sample",
signature(x = "SparkDataFrame"),
function(x, withReplacement = FALSE, fraction, seed) {
if (!is.numeric(fraction)) {
stop(paste("fraction must be numeric; however, got", class(fraction)))
}
if (!is.logical(withReplacement)) {
stop(paste("withReplacement must be logical; however, got", class(withReplacement)))
}
if (!missing(seed)) {
if (is.null(seed)) {
stop("seed must not be NULL or NA; however, got NULL")
}
if (is.na(seed)) {
stop("seed must not be NULL or NA; however, got NA")
}
# TODO : Figure out how to send integer as java.lang.Long to JVM so
# we can send seed as an argument through callJMethod
sdf <- handledCallJMethod(x@sdf, "sample", as.logical(withReplacement),
as.numeric(fraction), as.integer(seed))
} else {
sdf <- handledCallJMethod(x@sdf, "sample",
as.logical(withReplacement), as.numeric(fraction))
}
dataFrame(sdf)
})
#' @rdname sample
#' @aliases sample_frac,SparkDataFrame-method
#' @name sample_frac
#' @note sample_frac since 1.4.0
setMethod("sample_frac",
signature(x = "SparkDataFrame"),
function(x, withReplacement = FALSE, fraction, seed) {
sample(x, withReplacement, fraction, seed)
})
#' Returns the number of rows in a SparkDataFrame
#'
#' @param x a SparkDataFrame.
#' @family SparkDataFrame functions
#' @rdname nrow
#' @name nrow
#' @aliases count,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' count(df)
#' }
#' @note count since 1.4.0
setMethod("count",
signature(x = "SparkDataFrame"),
function(x) {
callJMethod(x@sdf, "count")
})
#' @name nrow
#' @rdname nrow
#' @aliases nrow,SparkDataFrame-method
#' @note nrow since 1.5.0
setMethod("nrow",
signature(x = "SparkDataFrame"),
function(x) {
count(x)
})
#' Returns the number of columns in a SparkDataFrame
#'
#' @param x a SparkDataFrame
#'
#' @family SparkDataFrame functions
#' @rdname ncol
#' @name ncol
#' @aliases ncol,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' ncol(df)
#' }
#' @note ncol since 1.5.0
setMethod("ncol",
signature(x = "SparkDataFrame"),
function(x) {
length(columns(x))
})
#' Returns the dimensions of SparkDataFrame
#'
#' Returns the dimensions (number of rows and columns) of a SparkDataFrame
#' @param x a SparkDataFrame
#'
#' @family SparkDataFrame functions
#' @rdname dim
#' @aliases dim,SparkDataFrame-method
#' @name dim
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' dim(df)
#' }
#' @note dim since 1.5.0
setMethod("dim",
signature(x = "SparkDataFrame"),
function(x) {
c(count(x), ncol(x))
})
#' Collects all the elements of a SparkDataFrame and coerces them into an R data.frame.
#'
#' @param x a SparkDataFrame.
#' @param stringsAsFactors (Optional) a logical indicating whether or not string columns
#' should be converted to factors. FALSE by default.
#' @param ... further arguments to be passed to or from other methods.
#'
#' @family SparkDataFrame functions
#' @rdname collect
#' @aliases collect,SparkDataFrame-method
#' @name collect
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' collected <- collect(df)
#' class(collected)
#' firstName <- names(collected)[1]
#' }
#' @note collect since 1.4.0
setMethod("collect",
signature(x = "SparkDataFrame"),
function(x, stringsAsFactors = FALSE) {
dtypes <- dtypes(x)
ncol <- length(dtypes)
if (ncol <= 0) {
# empty data.frame with 0 columns and 0 rows
data.frame()
} else {
# listCols is a list of columns
listCols <- callJStatic("org.apache.spark.sql.api.r.SQLUtils", "dfToCols", x@sdf)
stopifnot(length(listCols) == ncol)
# An empty data.frame with 0 columns and number of rows as collected
nrow <- length(listCols[[1]])
if (nrow <= 0) {
df <- data.frame()
} else {
df <- data.frame(row.names = 1 : nrow)
}
# Append columns one by one
for (colIndex in 1 : ncol) {
# Note: appending a column of list type into a data.frame so that
# data of complex type can be held. But getting a cell from a column
# of list type returns a list instead of a vector. So for columns of
# non-complex type, append them as vector.
#
# For columns of complex type, be careful to access them.
# Get a column of complex type returns a list.
# Get a cell from a column of complex type returns a list instead of a vector.
col <- listCols[[colIndex]]
if (length(col) <= 0) {
df[[colIndex]] <- col
} else {
colType <- dtypes[[colIndex]][[2]]
if (is.null(PRIMITIVE_TYPES[[colType]])) {
specialtype <- specialtypeshandle(colType)
if (!is.null(specialtype)) {
colType <- specialtype
}
}
# Note that "binary" columns behave like complex types.
if (!is.null(PRIMITIVE_TYPES[[colType]]) && colType != "binary") {
vec <- do.call(c, col)
stopifnot(class(vec) != "list")
class(vec) <- PRIMITIVE_TYPES[[colType]]
if (is.character(vec) && stringsAsFactors) {
vec <- as.factor(vec)
}
df[[colIndex]] <- vec
} else {
df[[colIndex]] <- col
}
}
}
names(df) <- names(x)
df
}
})
#' Limit
#'
#' Limit the resulting SparkDataFrame to the number of rows specified.
#'
#' @param x A SparkDataFrame
#' @param num The number of rows to return
#' @return A new SparkDataFrame containing the number of rows specified.
#'
#' @family SparkDataFrame functions
#' @rdname limit
#' @name limit
#' @aliases limit,SparkDataFrame,numeric-method
#' @export
#' @examples
#' \dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' limitedDF <- limit(df, 10)
#' }
#' @note limit since 1.4.0
setMethod("limit",
signature(x = "SparkDataFrame", num = "numeric"),
function(x, num) {
res <- callJMethod(x@sdf, "limit", as.integer(num))
dataFrame(res)
})
#' Take the first NUM rows of a SparkDataFrame and return the results as a R data.frame
#'
#' @param x a SparkDataFrame.
#' @param num number of rows to take.
#' @family SparkDataFrame functions
#' @rdname take
#' @name take
#' @aliases take,SparkDataFrame,numeric-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' take(df, 2)
#' }
#' @note take since 1.4.0
setMethod("take",
signature(x = "SparkDataFrame", num = "numeric"),
function(x, num) {
limited <- limit(x, num)
collect(limited)
})
#' Head
#'
#' Return the first \code{num} rows of a SparkDataFrame as a R data.frame. If \code{num} is not
#' specified, then head() returns the first 6 rows as with R data.frame.
#'
#' @param x a SparkDataFrame.
#' @param num the number of rows to return. Default is 6.
#' @return A data.frame.
#'
#' @family SparkDataFrame functions
#' @aliases head,SparkDataFrame-method
#' @rdname head
#' @name head
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' head(df)
#' }
#' @note head since 1.4.0
setMethod("head",
signature(x = "SparkDataFrame"),
function(x, num = 6L) {
# Default num is 6L in keeping with R's data.frame convention
take(x, num)
})
#' Return the first row of a SparkDataFrame
#'
#' @param x a SparkDataFrame or a column used in aggregation function.
#' @param ... further arguments to be passed to or from other methods.
#'
#' @family SparkDataFrame functions
#' @aliases first,SparkDataFrame-method
#' @rdname first
#' @name first
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' first(df)
#' }
#' @note first(SparkDataFrame) since 1.4.0
setMethod("first",
signature(x = "SparkDataFrame"),
function(x) {
take(x, 1)
})
#' toRDD
#'
#' Converts a SparkDataFrame to an RDD while preserving column names.
#'
#' @param x A SparkDataFrame
#'
#' @noRd
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' rdd <- toRDD(df)
#'}
setMethod("toRDD",
signature(x = "SparkDataFrame"),
function(x) {
jrdd <- callJStatic("org.apache.spark.sql.api.r.SQLUtils", "dfToRowRDD", x@sdf)
colNames <- callJMethod(x@sdf, "columns")
rdd <- RDD(jrdd, serializedMode = "row")
lapply(rdd, function(row) {
names(row) <- colNames
row
})
})
#' GroupBy
#'
#' Groups the SparkDataFrame using the specified columns, so we can run aggregation on them.
#'
#' @param x a SparkDataFrame.
#' @param ... character name(s) or Column(s) to group on.
#' @return A GroupedData.
#' @family SparkDataFrame functions
#' @aliases groupBy,SparkDataFrame-method
#' @rdname groupBy
#' @name groupBy
#' @export
#' @examples
#' \dontrun{
#' # Compute the average for all numeric columns grouped by department.
#' avg(groupBy(df, "department"))
#'
#' # Compute the max age and average salary, grouped by department and gender.
#' agg(groupBy(df, "department", "gender"), salary="avg", "age" -> "max")
#' }
#' @note groupBy since 1.4.0
#' @seealso \link{agg}, \link{cube}, \link{rollup}
setMethod("groupBy",
signature(x = "SparkDataFrame"),
function(x, ...) {
cols <- list(...)
if (length(cols) >= 1 && class(cols[[1]]) == "character") {
sgd <- callJMethod(x@sdf, "groupBy", cols[[1]], cols[-1])
} else {
jcol <- lapply(cols, function(c) { c@jc })
sgd <- callJMethod(x@sdf, "groupBy", jcol)
}
groupedData(sgd)
})
#' @rdname groupBy
#' @name group_by
#' @aliases group_by,SparkDataFrame-method
#' @note group_by since 1.4.0
setMethod("group_by",
signature(x = "SparkDataFrame"),
function(x, ...) {
groupBy(x, ...)
})
#' Summarize data across columns
#'
#' Compute aggregates by specifying a list of columns
#'
#' @family SparkDataFrame functions
#' @aliases agg,SparkDataFrame-method
#' @rdname summarize
#' @name agg
#' @export
#' @note agg since 1.4.0
setMethod("agg",
signature(x = "SparkDataFrame"),
function(x, ...) {
agg(groupBy(x), ...)
})
#' @rdname summarize
#' @name summarize
#' @aliases summarize,SparkDataFrame-method
#' @note summarize since 1.4.0
setMethod("summarize",
signature(x = "SparkDataFrame"),
function(x, ...) {
agg(x, ...)
})
dapplyInternal <- function(x, func, schema) {
if (is.character(schema)) {
schema <- structType(schema)
}
packageNamesArr <- serialize(.sparkREnv[[".packages"]],
connection = NULL)
broadcastArr <- lapply(ls(.broadcastNames),
function(name) { get(name, .broadcastNames) })
sdf <- callJStatic(
"org.apache.spark.sql.api.r.SQLUtils",
"dapply",
x@sdf,
serialize(cleanClosure(func), connection = NULL),
packageNamesArr,
broadcastArr,
if (is.null(schema)) { schema } else { schema$jobj })
dataFrame(sdf)
}
setClassUnion("characterOrstructType", c("character", "structType"))
#' dapply
#'
#' Apply a function to each partition of a SparkDataFrame.
#'
#' @param x A SparkDataFrame
#' @param func A function to be applied to each partition of the SparkDataFrame.
#' func should have only one parameter, to which a R data.frame corresponds
#' to each partition will be passed.
#' The output of func should be a R data.frame.
#' @param schema The schema of the resulting SparkDataFrame after the function is applied.
#' It must match the output of func. Since Spark 2.3, the DDL-formatted string
#' is also supported for the schema.
#' @family SparkDataFrame functions
#' @rdname dapply
#' @aliases dapply,SparkDataFrame,function,characterOrstructType-method
#' @name dapply
#' @seealso \link{dapplyCollect}
#' @export
#' @examples
#' \dontrun{
#' df <- createDataFrame(iris)
#' df1 <- dapply(df, function(x) { x }, schema(df))
#' collect(df1)
#'
#' # filter and add a column
#' df <- createDataFrame(
#' list(list(1L, 1, "1"), list(2L, 2, "2"), list(3L, 3, "3")),
#' c("a", "b", "c"))
#' schema <- structType(structField("a", "integer"), structField("b", "double"),
#' structField("c", "string"), structField("d", "integer"))
#' df1 <- dapply(
#' df,
#' function(x) {
#' y <- x[x[1] > 1, ]
#' y <- cbind(y, y[1] + 1L)
#' },
#' schema)
#'
#' # The schema also can be specified in a DDL-formatted string.
#' schema <- "a INT, d DOUBLE, c STRING, d INT"
#' df1 <- dapply(
#' df,
#' function(x) {
#' y <- x[x[1] > 1, ]
#' y <- cbind(y, y[1] + 1L)
#' },
#' schema)
#'
#' collect(df1)
#' # the result
#' # a b c d
#' # 1 2 2 2 3
#' # 2 3 3 3 4
#' }
#' @note dapply since 2.0.0
setMethod("dapply",
signature(x = "SparkDataFrame", func = "function", schema = "characterOrstructType"),
function(x, func, schema) {
dapplyInternal(x, func, schema)
})
#' dapplyCollect
#'
#' Apply a function to each partition of a SparkDataFrame and collect the result back
#' to R as a data.frame.
#'
#' @param x A SparkDataFrame
#' @param func A function to be applied to each partition of the SparkDataFrame.
#' func should have only one parameter, to which a R data.frame corresponds
#' to each partition will be passed.
#' The output of func should be a R data.frame.
#' @family SparkDataFrame functions
#' @rdname dapplyCollect
#' @aliases dapplyCollect,SparkDataFrame,function-method
#' @name dapplyCollect
#' @seealso \link{dapply}
#' @export
#' @examples
#' \dontrun{
#' df <- createDataFrame(iris)
#' ldf <- dapplyCollect(df, function(x) { x })
#'
#' # filter and add a column
#' df <- createDataFrame(
#' list(list(1L, 1, "1"), list(2L, 2, "2"), list(3L, 3, "3")),
#' c("a", "b", "c"))
#' ldf <- dapplyCollect(
#' df,
#' function(x) {
#' y <- x[x[1] > 1, ]
#' y <- cbind(y, y[1] + 1L)
#' })
#' # the result
#' # a b c d
#' # 2 2 2 3
#' # 3 3 3 4
#' }
#' @note dapplyCollect since 2.0.0
setMethod("dapplyCollect",
signature(x = "SparkDataFrame", func = "function"),
function(x, func) {
df <- dapplyInternal(x, func, NULL)
content <- callJMethod(df@sdf, "collect")
# content is a list of items of struct type. Each item has a single field
# which is a serialized data.frame corresponds to one partition of the
# SparkDataFrame.
ldfs <- lapply(content, function(x) { unserialize(x[[1]]) })
ldf <- do.call(rbind, ldfs)
row.names(ldf) <- NULL
ldf
})
#' gapply
#'
#' Groups the SparkDataFrame using the specified columns and applies the R function to each
#' group.
#'
#' @param cols grouping columns.
#' @param func a function to be applied to each group partition specified by grouping
#' column of the SparkDataFrame. The function \code{func} takes as argument
#' a key - grouping columns and a data frame - a local R data.frame.
#' The output of \code{func} is a local R data.frame.
#' @param schema the schema of the resulting SparkDataFrame after the function is applied.
#' The schema must match to output of \code{func}. It has to be defined for each
#' output column with preferred output column name and corresponding data type.
#' Since Spark 2.3, the DDL-formatted string is also supported for the schema.
#' @return A SparkDataFrame.
#' @family SparkDataFrame functions
#' @aliases gapply,SparkDataFrame-method
#' @rdname gapply
#' @name gapply
#' @seealso \link{gapplyCollect}
#' @export
#' @examples
#'
#' \dontrun{
#' Computes the arithmetic mean of the second column by grouping
#' on the first and third columns. Output the grouping values and the average.
#'
#' df <- createDataFrame (
#' list(list(1L, 1, "1", 0.1), list(1L, 2, "1", 0.2), list(3L, 3, "3", 0.3)),
#' c("a", "b", "c", "d"))
#'
#' Here our output contains three columns, the key which is a combination of two
#' columns with data types integer and string and the mean which is a double.
#' schema <- structType(structField("a", "integer"), structField("c", "string"),
#' structField("avg", "double"))
#' result <- gapply(
#' df,
#' c("a", "c"),
#' function(key, x) {
#' y <- data.frame(key, mean(x$b), stringsAsFactors = FALSE)
#' }, schema)
#'
#' The schema also can be specified in a DDL-formatted string.
#' schema <- "a INT, c STRING, avg DOUBLE"
#' result <- gapply(
#' df,
#' c("a", "c"),
#' function(key, x) {
#' y <- data.frame(key, mean(x$b), stringsAsFactors = FALSE)
#' }, schema)
#'
#' We can also group the data and afterwards call gapply on GroupedData.
#' For Example:
#' gdf <- group_by(df, "a", "c")
#' result <- gapply(
#' gdf,
#' function(key, x) {
#' y <- data.frame(key, mean(x$b), stringsAsFactors = FALSE)
#' }, schema)
#' collect(result)
#'
#' Result
#' ------
#' a c avg
#' 3 3 3.0
#' 1 1 1.5
#'
#' Fits linear models on iris dataset by grouping on the 'Species' column and
#' using 'Sepal_Length' as a target variable, 'Sepal_Width', 'Petal_Length'
#' and 'Petal_Width' as training features.
#'
#' df <- createDataFrame (iris)
#' schema <- structType(structField("(Intercept)", "double"),
#' structField("Sepal_Width", "double"),structField("Petal_Length", "double"),
#' structField("Petal_Width", "double"))
#' df1 <- gapply(
#' df,
#' df$"Species",
#' function(key, x) {
#' m <- suppressWarnings(lm(Sepal_Length ~
#' Sepal_Width + Petal_Length + Petal_Width, x))
#' data.frame(t(coef(m)))
#' }, schema)
#' collect(df1)
#'
#' Result
#' ---------
#' Model (Intercept) Sepal_Width Petal_Length Petal_Width
#' 1 0.699883 0.3303370 0.9455356 -0.1697527
#' 2 1.895540 0.3868576 0.9083370 -0.6792238
#' 3 2.351890 0.6548350 0.2375602 0.2521257
#'
#'}
#' @note gapply(SparkDataFrame) since 2.0.0
setMethod("gapply",
signature(x = "SparkDataFrame"),
function(x, cols, func, schema) {
grouped <- do.call("groupBy", c(x, cols))
gapply(grouped, func, schema)
})
#' gapplyCollect
#'
#' Groups the SparkDataFrame using the specified columns, applies the R function to each
#' group and collects the result back to R as data.frame.
#'
#' @param cols grouping columns.
#' @param func a function to be applied to each group partition specified by grouping
#' column of the SparkDataFrame. The function \code{func} takes as argument
#' a key - grouping columns and a data frame - a local R data.frame.
#' The output of \code{func} is a local R data.frame.
#' @return A data.frame.
#' @family SparkDataFrame functions
#' @aliases gapplyCollect,SparkDataFrame-method
#' @rdname gapplyCollect
#' @name gapplyCollect
#' @seealso \link{gapply}
#' @export
#' @examples
#'
#' \dontrun{
#' Computes the arithmetic mean of the second column by grouping
#' on the first and third columns. Output the grouping values and the average.
#'
#' df <- createDataFrame (
#' list(list(1L, 1, "1", 0.1), list(1L, 2, "1", 0.2), list(3L, 3, "3", 0.3)),
#' c("a", "b", "c", "d"))
#'
#' result <- gapplyCollect(
#' df,
#' c("a", "c"),
#' function(key, x) {
#' y <- data.frame(key, mean(x$b), stringsAsFactors = FALSE)
#' colnames(y) <- c("key_a", "key_c", "mean_b")
#' y
#' })
#'
#' We can also group the data and afterwards call gapply on GroupedData.
#' For Example:
#' gdf <- group_by(df, "a", "c")
#' result <- gapplyCollect(
#' gdf,
#' function(key, x) {
#' y <- data.frame(key, mean(x$b), stringsAsFactors = FALSE)
#' colnames(y) <- c("key_a", "key_c", "mean_b")
#' y
#' })
#'
#' Result
#' ------
#' key_a key_c mean_b
#' 3 3 3.0
#' 1 1 1.5
#'
#' Fits linear models on iris dataset by grouping on the 'Species' column and
#' using 'Sepal_Length' as a target variable, 'Sepal_Width', 'Petal_Length'
#' and 'Petal_Width' as training features.
#'
#' df <- createDataFrame (iris)
#' result <- gapplyCollect(
#' df,
#' df$"Species",
#' function(key, x) {
#' m <- suppressWarnings(lm(Sepal_Length ~
#' Sepal_Width + Petal_Length + Petal_Width, x))
#' data.frame(t(coef(m)))
#' })
#'
#' Result
#'---------
#' Model X.Intercept. Sepal_Width Petal_Length Petal_Width
#' 1 0.699883 0.3303370 0.9455356 -0.1697527
#' 2 1.895540 0.3868576 0.9083370 -0.6792238
#' 3 2.351890 0.6548350 0.2375602 0.2521257
#'
#'}
#' @note gapplyCollect(SparkDataFrame) since 2.0.0
setMethod("gapplyCollect",
signature(x = "SparkDataFrame"),
function(x, cols, func) {
grouped <- do.call("groupBy", c(x, cols))
gapplyCollect(grouped, func)
})
############################## RDD Map Functions ##################################
# All of the following functions mirror the existing RDD map functions, #
# but allow for use with DataFrames by first converting to an RRDD before calling #
# the requested map function. #
###################################################################################
#' @rdname lapply
#' @noRd
setMethod("lapply",
signature(X = "SparkDataFrame", FUN = "function"),
function(X, FUN) {
rdd <- toRDD(X)
lapply(rdd, FUN)
})
#' @rdname lapply
#' @noRd
setMethod("map",
signature(X = "SparkDataFrame", FUN = "function"),
function(X, FUN) {
lapply(X, FUN)
})
#' @rdname flatMap
#' @noRd
setMethod("flatMap",
signature(X = "SparkDataFrame", FUN = "function"),
function(X, FUN) {
rdd <- toRDD(X)
flatMap(rdd, FUN)
})
#' @rdname lapplyPartition
#' @noRd
setMethod("lapplyPartition",
signature(X = "SparkDataFrame", FUN = "function"),
function(X, FUN) {
rdd <- toRDD(X)
lapplyPartition(rdd, FUN)
})
#' @rdname lapplyPartition
#' @noRd
setMethod("mapPartitions",
signature(X = "SparkDataFrame", FUN = "function"),
function(X, FUN) {
lapplyPartition(X, FUN)
})
#' @rdname foreach
#' @noRd
setMethod("foreach",
signature(x = "SparkDataFrame", func = "function"),
function(x, func) {
rdd <- toRDD(x)
foreach(rdd, func)
})
#' @rdname foreach
#' @noRd
setMethod("foreachPartition",
signature(x = "SparkDataFrame", func = "function"),
function(x, func) {
rdd <- toRDD(x)
foreachPartition(rdd, func)
})
############################## SELECT ##################################
getColumn <- function(x, c) {
column(callJMethod(x@sdf, "col", c))
}
setColumn <- function(x, c, value) {
if (class(value) != "Column" && !is.null(value)) {
if (isAtomicLengthOne(value)) {
value <- lit(value)
} else {
stop("value must be a Column, literal value as atomic in length of 1, or NULL")
}
}
if (is.null(value)) {
nx <- drop(x, c)
} else {
nx <- withColumn(x, c, value)
}
nx
}
#' @param name name of a Column (without being wrapped by \code{""}).
#' @rdname select
#' @name $
#' @aliases $,SparkDataFrame-method
#' @note $ since 1.4.0
setMethod("$", signature(x = "SparkDataFrame"),
function(x, name) {
getColumn(x, name)
})
#' @param value a Column or an atomic vector in the length of 1 as literal value, or \code{NULL}.
#' If \code{NULL}, the specified Column is dropped.
#' @rdname select
#' @name $<-
#' @aliases $<-,SparkDataFrame-method
#' @note $<- since 1.4.0
setMethod("$<-", signature(x = "SparkDataFrame"),
function(x, name, value) {
nx <- setColumn(x, name, value)
x@sdf <- nx@sdf
x
})
setClassUnion("numericOrcharacter", c("numeric", "character"))
#' @rdname subset
#' @name [[
#' @aliases [[,SparkDataFrame,numericOrcharacter-method
#' @note [[ since 1.4.0
setMethod("[[", signature(x = "SparkDataFrame", i = "numericOrcharacter"),
function(x, i) {
if (length(i) > 1) {
warning("Subset index has length > 1. Only the first index is used.")
i <- i[1]
}
if (is.numeric(i)) {
cols <- columns(x)
i <- cols[[i]]
}
getColumn(x, i)
})
#' @rdname subset
#' @name [[<-
#' @aliases [[<-,SparkDataFrame,numericOrcharacter-method
#' @note [[<- since 2.1.1
setMethod("[[<-", signature(x = "SparkDataFrame", i = "numericOrcharacter"),
function(x, i, value) {
if (length(i) > 1) {
warning("Subset index has length > 1. Only the first index is used.")
i <- i[1]
}
if (is.numeric(i)) {
cols <- columns(x)
i <- cols[[i]]
}
nx <- setColumn(x, i, value)
x@sdf <- nx@sdf
x
})
#' @rdname subset
#' @name [
#' @aliases [,SparkDataFrame-method
#' @note [ since 1.4.0
setMethod("[", signature(x = "SparkDataFrame"),
function(x, i, j, ..., drop = F) {
# Perform filtering first if needed
filtered <- if (missing(i)) {
x
} else {
if (class(i) != "Column") {
stop(paste0("Expressions other than filtering predicates are not supported ",
"in the first parameter of extract operator [ or subset() method."))
}
filter(x, i)
}
# If something is to be projected, then do so on the filtered SparkDataFrame
if (missing(j)) {
filtered
} else {
if (is.numeric(j)) {
cols <- columns(filtered)
j <- cols[j]
}
if (length(j) > 1) {
j <- as.list(j)
}
selected <- select(filtered, j)
# Acknowledge parameter drop. Return a Column or SparkDataFrame accordingly
if (ncol(selected) == 1 & drop == T) {
getColumn(selected, names(selected))
} else {
selected
}
}
})
#' Subset
#'
#' Return subsets of SparkDataFrame according to given conditions
#' @param x a SparkDataFrame.
#' @param i,subset (Optional) a logical expression to filter on rows.
#' For extract operator [[ and replacement operator [[<-, the indexing parameter for
#' a single Column.
#' @param j,select expression for the single Column or a list of columns to select from the
#' SparkDataFrame.
#' @param drop if TRUE, a Column will be returned if the resulting dataset has only one column.
#' Otherwise, a SparkDataFrame will always be returned.
#' @param value a Column or an atomic vector in the length of 1 as literal value, or \code{NULL}.
#' If \code{NULL}, the specified Column is dropped.
#' @param ... currently not used.
#' @return A new SparkDataFrame containing only the rows that meet the condition with selected
#' columns.
#' @export
#' @family SparkDataFrame functions
#' @aliases subset,SparkDataFrame-method
#' @seealso \link{withColumn}
#' @rdname subset
#' @name subset
#' @family subsetting functions
#' @examples
#' \dontrun{
#' # Columns can be selected using [[ and [
#' df[[2]] == df[["age"]]
#' df[,2] == df[,"age"]
#' df[,c("name", "age")]
#' # Or to filter rows
#' df[df$age > 20,]
#' # SparkDataFrame can be subset on both rows and Columns
#' df[df$name == "Smith", c(1,2)]
#' df[df$age %in% c(19, 30), 1:2]
#' subset(df, df$age %in% c(19, 30), 1:2)
#' subset(df, df$age %in% c(19), select = c(1,2))
#' subset(df, select = c(1,2))
#' # Columns can be selected and set
#' df[["age"]] <- 23
#' df[[1]] <- df$age
#' df[[2]] <- NULL # drop column
#' }
#' @note subset since 1.5.0
setMethod("subset", signature(x = "SparkDataFrame"),
function(x, subset, select, drop = F, ...) {
if (missing(subset)) {
x[, select, drop = drop, ...]
} else {
x[subset, select, drop = drop, ...]
}
})
#' Select
#'
#' Selects a set of columns with names or Column expressions.
#' @param x a SparkDataFrame.
#' @param col a list of columns or single Column or name.
#' @param ... additional column(s) if only one column is specified in \code{col}.
#' If more than one column is assigned in \code{col}, \code{...}
#' should be left empty.
#' @return A new SparkDataFrame with selected columns.
#' @export
#' @family SparkDataFrame functions
#' @rdname select
#' @aliases select,SparkDataFrame,character-method
#' @name select
#' @family subsetting functions
#' @examples
#' \dontrun{
#' select(df, "*")
#' select(df, "col1", "col2")
#' select(df, df$name, df$age + 1)
#' select(df, c("col1", "col2"))
#' select(df, list(df$name, df$age + 1))
#' # Similar to R data frames columns can also be selected using $
#' df[,df$age]
#' }
#' @note select(SparkDataFrame, character) since 1.4.0
setMethod("select", signature(x = "SparkDataFrame", col = "character"),
function(x, col, ...) {
if (length(col) > 1) {
if (length(list(...)) > 0) {
stop("To select multiple columns, use a character vector or list for col")
}
select(x, as.list(col))
} else {
sdf <- callJMethod(x@sdf, "select", col, list(...))
dataFrame(sdf)
}
})
#' @rdname select
#' @export
#' @aliases select,SparkDataFrame,Column-method
#' @note select(SparkDataFrame, Column) since 1.4.0
setMethod("select", signature(x = "SparkDataFrame", col = "Column"),
function(x, col, ...) {
jcols <- lapply(list(col, ...), function(c) {
c@jc
})
sdf <- callJMethod(x@sdf, "select", jcols)
dataFrame(sdf)
})
#' @rdname select
#' @export
#' @aliases select,SparkDataFrame,list-method
#' @note select(SparkDataFrame, list) since 1.4.0
setMethod("select",
signature(x = "SparkDataFrame", col = "list"),
function(x, col) {
cols <- lapply(col, function(c) {
if (class(c) == "Column") {
c@jc
} else {
col(c)@jc
}
})
sdf <- callJMethod(x@sdf, "select", cols)
dataFrame(sdf)
})
#' SelectExpr
#'
#' Select from a SparkDataFrame using a set of SQL expressions.
#'
#' @param x A SparkDataFrame to be selected from.
#' @param expr A string containing a SQL expression
#' @param ... Additional expressions
#' @return A SparkDataFrame
#' @family SparkDataFrame functions
#' @aliases selectExpr,SparkDataFrame,character-method
#' @rdname selectExpr
#' @name selectExpr
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' selectExpr(df, "col1", "(col2 * 5) as newCol")
#' }
#' @note selectExpr since 1.4.0
setMethod("selectExpr",
signature(x = "SparkDataFrame", expr = "character"),
function(x, expr, ...) {
exprList <- list(expr, ...)
sdf <- callJMethod(x@sdf, "selectExpr", exprList)
dataFrame(sdf)
})
#' WithColumn
#'
#' Return a new SparkDataFrame by adding a column or replacing the existing column
#' that has the same name.
#'
#' @param x a SparkDataFrame.
#' @param colName a column name.
#' @param col a Column expression, or an atomic vector in the length of 1 as literal value.
#' @return A SparkDataFrame with the new column added or the existing column replaced.
#' @family SparkDataFrame functions
#' @aliases withColumn,SparkDataFrame,character-method
#' @rdname withColumn
#' @name withColumn
#' @seealso \link{rename} \link{mutate} \link{subset}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' newDF <- withColumn(df, "newCol", df$col1 * 5)
#' # Replace an existing column
#' newDF2 <- withColumn(newDF, "newCol", newDF$col1)
#' newDF3 <- withColumn(newDF, "newCol", 42)
#' # Use extract operator to set an existing or new column
#' df[["age"]] <- 23
#' df[[2]] <- df$col1
#' df[[2]] <- NULL # drop column
#' }
#' @note withColumn since 1.4.0
setMethod("withColumn",
signature(x = "SparkDataFrame", colName = "character"),
function(x, colName, col) {
if (class(col) != "Column") {
if (!isAtomicLengthOne(col)) stop("Literal value must be atomic in length of 1")
col <- lit(col)
}
sdf <- callJMethod(x@sdf, "withColumn", colName, col@jc)
dataFrame(sdf)
})
#' Mutate
#'
#' Return a new SparkDataFrame with the specified columns added or replaced.
#'
#' @param .data a SparkDataFrame.
#' @param ... additional column argument(s) each in the form name = col.
#' @return A new SparkDataFrame with the new columns added or replaced.
#' @family SparkDataFrame functions
#' @aliases mutate,SparkDataFrame-method
#' @rdname mutate
#' @name mutate
#' @seealso \link{rename} \link{withColumn}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' newDF <- mutate(df, newCol = df$col1 * 5, newCol2 = df$col1 * 2)
#' names(newDF) # Will contain newCol, newCol2
#' newDF2 <- transform(df, newCol = df$col1 / 5, newCol2 = df$col1 * 2)
#'
#' df <- createDataFrame(list(list("Andy", 30L), list("Justin", 19L)), c("name", "age"))
#' # Replace the "age" column
#' df1 <- mutate(df, age = df$age + 1L)
#' }
#' @note mutate since 1.4.0
setMethod("mutate",
signature(.data = "SparkDataFrame"),
function(.data, ...) {
x <- .data
cols <- list(...)
if (length(cols) <= 0) {
return(x)
}
lapply(cols, function(col) {
stopifnot(class(col) == "Column")
})
# Check if there is any duplicated column name in the DataFrame
dfCols <- columns(x)
if (length(unique(dfCols)) != length(dfCols)) {
stop("Error: found duplicated column name in the DataFrame")
}
# TODO: simplify the implementation of this method after SPARK-12225 is resolved.
# For named arguments, use the names for arguments as the column names
# For unnamed arguments, use the argument symbols as the column names
args <- sapply(substitute(list(...))[-1], deparse)
ns <- names(cols)
if (!is.null(ns)) {
lapply(seq_along(args), function(i) {
if (ns[[i]] != "") {
args[[i]] <<- ns[[i]]
}
})
}
ns <- args
# The last column of the same name in the specific columns takes effect
deDupCols <- list()
for (i in 1:length(cols)) {
deDupCols[[ns[[i]]]] <- alias(cols[[i]], ns[[i]])
}
# Construct the column list for projection
colList <- lapply(dfCols, function(col) {
if (!is.null(deDupCols[[col]])) {
# Replace existing column
tmpCol <- deDupCols[[col]]
deDupCols[[col]] <<- NULL
tmpCol
} else {
col(col)
}
})
do.call(select, c(x, colList, deDupCols))
})
#' @param _data a SparkDataFrame.
#' @export
#' @rdname mutate
#' @aliases transform,SparkDataFrame-method
#' @name transform
#' @note transform since 1.5.0
setMethod("transform",
signature(`_data` = "SparkDataFrame"),
function(`_data`, ...) {
mutate(`_data`, ...)
})
#' rename
#'
#' Rename an existing column in a SparkDataFrame.
#'
#' @param x A SparkDataFrame
#' @param existingCol The name of the column you want to change.
#' @param newCol The new column name.
#' @return A SparkDataFrame with the column name changed.
#' @family SparkDataFrame functions
#' @rdname rename
#' @name withColumnRenamed
#' @aliases withColumnRenamed,SparkDataFrame,character,character-method
#' @seealso \link{mutate}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' newDF <- withColumnRenamed(df, "col1", "newCol1")
#' }
#' @note withColumnRenamed since 1.4.0
setMethod("withColumnRenamed",
signature(x = "SparkDataFrame", existingCol = "character", newCol = "character"),
function(x, existingCol, newCol) {
cols <- lapply(columns(x), function(c) {
if (c == existingCol) {
alias(col(c), newCol)
} else {
col(c)
}
})
select(x, cols)
})
#' @param ... A named pair of the form new_column_name = existing_column
#' @rdname rename
#' @name rename
#' @aliases rename,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' newDF <- rename(df, col1 = df$newCol1)
#' }
#' @note rename since 1.4.0
setMethod("rename",
signature(x = "SparkDataFrame"),
function(x, ...) {
renameCols <- list(...)
stopifnot(length(renameCols) > 0)
stopifnot(class(renameCols[[1]]) == "Column")
newNames <- names(renameCols)
oldNames <- lapply(renameCols, function(col) {
callJMethod(col@jc, "toString")
})
cols <- lapply(columns(x), function(c) {
if (c %in% oldNames) {
alias(col(c), newNames[[match(c, oldNames)]])
} else {
col(c)
}
})
select(x, cols)
})
setClassUnion("characterOrColumn", c("character", "Column"))
#' Arrange Rows by Variables
#'
#' Sort a SparkDataFrame by the specified column(s).
#'
#' @param x a SparkDataFrame to be sorted.
#' @param col a character or Column object indicating the fields to sort on
#' @param ... additional sorting fields
#' @param decreasing a logical argument indicating sorting order for columns when
#' a character vector is specified for col
#' @return A SparkDataFrame where all elements are sorted.
#' @family SparkDataFrame functions
#' @aliases arrange,SparkDataFrame,Column-method
#' @rdname arrange
#' @name arrange
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' arrange(df, df$col1)
#' arrange(df, asc(df$col1), desc(abs(df$col2)))
#' arrange(df, "col1", decreasing = TRUE)
#' arrange(df, "col1", "col2", decreasing = c(TRUE, FALSE))
#' }
#' @note arrange(SparkDataFrame, Column) since 1.4.0
setMethod("arrange",
signature(x = "SparkDataFrame", col = "Column"),
function(x, col, ...) {
jcols <- lapply(list(col, ...), function(c) {
c@jc
})
sdf <- callJMethod(x@sdf, "sort", jcols)
dataFrame(sdf)
})
#' @rdname arrange
#' @name arrange
#' @aliases arrange,SparkDataFrame,character-method
#' @export
#' @note arrange(SparkDataFrame, character) since 1.4.0
setMethod("arrange",
signature(x = "SparkDataFrame", col = "character"),
function(x, col, ..., decreasing = FALSE) {
# all sorting columns
by <- list(col, ...)
if (length(decreasing) == 1) {
# in case only 1 boolean argument - decreasing value is specified,
# it will be used for all columns
decreasing <- rep(decreasing, length(by))
} else if (length(decreasing) != length(by)) {
stop("Arguments 'col' and 'decreasing' must have the same length")
}
# builds a list of columns of type Column
# example: [[1]] Column Species ASC
# [[2]] Column Petal_Length DESC
jcols <- lapply(seq_len(length(decreasing)), function(i){
if (decreasing[[i]]) {
desc(getColumn(x, by[[i]]))
} else {
asc(getColumn(x, by[[i]]))
}
})
do.call("arrange", c(x, jcols))
})
#' @rdname arrange
#' @aliases orderBy,SparkDataFrame,characterOrColumn-method
#' @export
#' @note orderBy(SparkDataFrame, characterOrColumn) since 1.4.0
setMethod("orderBy",
signature(x = "SparkDataFrame", col = "characterOrColumn"),
function(x, col, ...) {
arrange(x, col, ...)
})
#' Filter
#'
#' Filter the rows of a SparkDataFrame according to a given condition.
#'
#' @param x A SparkDataFrame to be sorted.
#' @param condition The condition to filter on. This may either be a Column expression
#' or a string containing a SQL statement
#' @return A SparkDataFrame containing only the rows that meet the condition.
#' @family SparkDataFrame functions
#' @aliases filter,SparkDataFrame,characterOrColumn-method
#' @rdname filter
#' @name filter
#' @family subsetting functions
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' filter(df, "col1 > 0")
#' filter(df, df$col2 != "abcdefg")
#' }
#' @note filter since 1.4.0
setMethod("filter",
signature(x = "SparkDataFrame", condition = "characterOrColumn"),
function(x, condition) {
if (class(condition) == "Column") {
condition <- condition@jc
}
sdf <- callJMethod(x@sdf, "filter", condition)
dataFrame(sdf)
})
#' @rdname filter
#' @name where
#' @aliases where,SparkDataFrame,characterOrColumn-method
#' @note where since 1.4.0
setMethod("where",
signature(x = "SparkDataFrame", condition = "characterOrColumn"),
function(x, condition) {
filter(x, condition)
})
#' dropDuplicates
#'
#' Returns a new SparkDataFrame with duplicate rows removed, considering only
#' the subset of columns.
#'
#' @param x A SparkDataFrame.
#' @param ... A character vector of column names or string column names.
#' If the first argument contains a character vector, the followings are ignored.
#' @return A SparkDataFrame with duplicate rows removed.
#' @family SparkDataFrame functions
#' @aliases dropDuplicates,SparkDataFrame-method
#' @rdname dropDuplicates
#' @name dropDuplicates
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' dropDuplicates(df)
#' dropDuplicates(df, "col1", "col2")
#' dropDuplicates(df, c("col1", "col2"))
#' }
#' @note dropDuplicates since 2.0.0
setMethod("dropDuplicates",
signature(x = "SparkDataFrame"),
function(x, ...) {
cols <- list(...)
if (length(cols) == 0) {
sdf <- callJMethod(x@sdf, "dropDuplicates", as.list(columns(x)))
} else {
if (!all(sapply(cols, function(c) { is.character(c) }))) {
stop("all columns names should be characters")
}
col <- cols[[1]]
if (length(col) > 1) {
sdf <- callJMethod(x@sdf, "dropDuplicates", as.list(col))
} else {
sdf <- callJMethod(x@sdf, "dropDuplicates", cols)
}
}
dataFrame(sdf)
})
#' Join
#'
#' Joins two SparkDataFrames based on the given join expression.
#'
#' @param x A SparkDataFrame
#' @param y A SparkDataFrame
#' @param joinExpr (Optional) The expression used to perform the join. joinExpr must be a
#' Column expression. If joinExpr is omitted, the default, inner join is attempted and an error is
#' thrown if it would be a Cartesian Product. For Cartesian join, use crossJoin instead.
#' @param joinType The type of join to perform, default 'inner'.
#' Must be one of: 'inner', 'cross', 'outer', 'full', 'full_outer',
#' 'left', 'left_outer', 'right', 'right_outer', 'left_semi', or 'left_anti'.
#' @return A SparkDataFrame containing the result of the join operation.
#' @family SparkDataFrame functions
#' @aliases join,SparkDataFrame,SparkDataFrame-method
#' @rdname join
#' @name join
#' @seealso \link{merge} \link{crossJoin}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df1 <- read.json(path)
#' df2 <- read.json(path2)
#' join(df1, df2, df1$col1 == df2$col2) # Performs an inner join based on expression
#' join(df1, df2, df1$col1 == df2$col2, "right_outer")
#' join(df1, df2) # Attempts an inner join
#' }
#' @note join since 1.4.0
setMethod("join",
signature(x = "SparkDataFrame", y = "SparkDataFrame"),
function(x, y, joinExpr = NULL, joinType = NULL) {
if (is.null(joinExpr)) {
# this may not fail until the planner checks for Cartesian join later on.
sdf <- callJMethod(x@sdf, "join", y@sdf)
} else {
if (class(joinExpr) != "Column") stop("joinExpr must be a Column")
if (is.null(joinType)) {
sdf <- callJMethod(x@sdf, "join", y@sdf, joinExpr@jc)
} else {
if (joinType %in% c("inner", "cross",
"outer", "full", "fullouter", "full_outer",
"left", "leftouter", "left_outer",
"right", "rightouter", "right_outer",
"left_semi", "leftsemi", "left_anti", "leftanti")) {
joinType <- gsub("_", "", joinType)
sdf <- callJMethod(x@sdf, "join", y@sdf, joinExpr@jc, joinType)
} else {
stop("joinType must be one of the following types: ",
"'inner', 'cross', 'outer', 'full', 'full_outer',",
"'left', 'left_outer', 'right', 'right_outer',",
"'left_semi', or 'left_anti'.")
}
}
}
dataFrame(sdf)
})
#' CrossJoin
#'
#' Returns Cartesian Product on two SparkDataFrames.
#'
#' @param x A SparkDataFrame
#' @param y A SparkDataFrame
#' @return A SparkDataFrame containing the result of the join operation.
#' @family SparkDataFrame functions
#' @aliases crossJoin,SparkDataFrame,SparkDataFrame-method
#' @rdname crossJoin
#' @name crossJoin
#' @seealso \link{merge} \link{join}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df1 <- read.json(path)
#' df2 <- read.json(path2)
#' crossJoin(df1, df2) # Performs a Cartesian
#' }
#' @note crossJoin since 2.1.0
setMethod("crossJoin",
signature(x = "SparkDataFrame", y = "SparkDataFrame"),
function(x, y) {
sdf <- callJMethod(x@sdf, "crossJoin", y@sdf)
dataFrame(sdf)
})
#' Merges two data frames
#'
#' @name merge
#' @param x the first data frame to be joined.
#' @param y the second data frame to be joined.
#' @param by a character vector specifying the join columns. If by is not
#' specified, the common column names in \code{x} and \code{y} will be used.
#' If by or both by.x and by.y are explicitly set to NULL or of length 0, the Cartesian
#' Product of x and y will be returned.
#' @param by.x a character vector specifying the joining columns for x.
#' @param by.y a character vector specifying the joining columns for y.
#' @param all a boolean value setting \code{all.x} and \code{all.y}
#' if any of them are unset.
#' @param all.x a boolean value indicating whether all the rows in x should
#' be including in the join.
#' @param all.y a boolean value indicating whether all the rows in y should
#' be including in the join.
#' @param sort a logical argument indicating whether the resulting columns should be sorted.
#' @param suffixes a string vector of length 2 used to make colnames of
#' \code{x} and \code{y} unique.
#' The first element is appended to each colname of \code{x}.
#' The second element is appended to each colname of \code{y}.
#' @param ... additional argument(s) passed to the method.
#' @details If all.x and all.y are set to FALSE, a natural join will be returned. If
#' all.x is set to TRUE and all.y is set to FALSE, a left outer join will
#' be returned. If all.x is set to FALSE and all.y is set to TRUE, a right
#' outer join will be returned. If all.x and all.y are set to TRUE, a full
#' outer join will be returned.
#' @family SparkDataFrame functions
#' @aliases merge,SparkDataFrame,SparkDataFrame-method
#' @rdname merge
#' @seealso \link{join} \link{crossJoin}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df1 <- read.json(path)
#' df2 <- read.json(path2)
#' merge(df1, df2) # Performs an inner join by common columns
#' merge(df1, df2, by = "col1") # Performs an inner join based on expression
#' merge(df1, df2, by.x = "col1", by.y = "col2", all.y = TRUE)
#' merge(df1, df2, by.x = "col1", by.y = "col2", all.x = TRUE)
#' merge(df1, df2, by.x = "col1", by.y = "col2", all.x = TRUE, all.y = TRUE)
#' merge(df1, df2, by.x = "col1", by.y = "col2", all = TRUE, sort = FALSE)
#' merge(df1, df2, by = "col1", all = TRUE, suffixes = c("-X", "-Y"))
#' merge(df1, df2, by = NULL) # Performs a Cartesian join
#' }
#' @note merge since 1.5.0
setMethod("merge",
signature(x = "SparkDataFrame", y = "SparkDataFrame"),
function(x, y, by = intersect(names(x), names(y)), by.x = by, by.y = by,
all = FALSE, all.x = all, all.y = all,
sort = TRUE, suffixes = c("_x", "_y"), ...) {
if (length(suffixes) != 2) {
stop("suffixes must have length 2")
}
# join type is identified based on the values of all, all.x and all.y
# default join type is inner, according to R it should be natural but since it
# is not supported in spark inner join is used
joinType <- "inner"
if (all || (all.x && all.y)) {
joinType <- "outer"
} else if (all.x) {
joinType <- "left_outer"
} else if (all.y) {
joinType <- "right_outer"
}
# join expression is based on by.x, by.y if both by.x and by.y are not missing
# or on by, if by.x or by.y are missing or have different lengths
if (length(by.x) > 0 && length(by.x) == length(by.y)) {
joinX <- by.x
joinY <- by.y
} else if (length(by) > 0) {
# if join columns have the same name for both dataframes,
# they are used in join expression
joinX <- by
joinY <- by
} else {
# if by or both by.x and by.y have length 0, use Cartesian Product
joinRes <- crossJoin(x, y)
return(joinRes)
}
# sets alias for making colnames unique in dataframes 'x' and 'y'
colsX <- genAliasesForIntersectedCols(x, by, suffixes[1])
colsY <- genAliasesForIntersectedCols(y, by, suffixes[2])
# selects columns with their aliases from dataframes
# in case same column names are present in both data frames
xsel <- select(x, colsX)
ysel <- select(y, colsY)
# generates join conditions and adds them into a list
# it also considers alias names of the columns while generating join conditions
joinColumns <- lapply(seq_len(length(joinX)), function(i) {
colX <- joinX[[i]]
colY <- joinY[[i]]
if (colX %in% by) {
colX <- paste(colX, suffixes[1], sep = "")
}
if (colY %in% by) {
colY <- paste(colY, suffixes[2], sep = "")
}
colX <- getColumn(xsel, colX)
colY <- getColumn(ysel, colY)
colX == colY
})
# concatenates join columns with '&' and executes join
joinExpr <- Reduce("&", joinColumns)
joinRes <- join(xsel, ysel, joinExpr, joinType)
# sorts the result by 'by' columns if sort = TRUE
if (sort && length(by) > 0) {
colNameWithSuffix <- paste(by, suffixes[2], sep = "")
joinRes <- do.call("arrange", c(joinRes, colNameWithSuffix, decreasing = FALSE))
}
joinRes
})
#' Creates a list of columns by replacing the intersected ones with aliases
#'
#' Creates a list of columns by replacing the intersected ones with aliases.
#' The name of the alias column is formed by concatanating the original column name and a suffix.
#'
#' @param x a SparkDataFrame
#' @param intersectedColNames a list of intersected column names of the SparkDataFrame
#' @param suffix a suffix for the column name
#' @return list of columns
#' @noRd
genAliasesForIntersectedCols <- function(x, intersectedColNames, suffix) {
allColNames <- names(x)
# sets alias for making colnames unique in dataframe 'x'
cols <- lapply(allColNames, function(colName) {
col <- getColumn(x, colName)
if (colName %in% intersectedColNames) {
newJoin <- paste(colName, suffix, sep = "")
if (newJoin %in% allColNames){
stop("The following column name: ", newJoin, " occurs more than once in the 'DataFrame'.",
"Please use different suffixes for the intersected columns.")
}
col <- alias(col, newJoin)
}
col
})
cols
}
#' Return a new SparkDataFrame containing the union of rows
#'
#' Return a new SparkDataFrame containing the union of rows in this SparkDataFrame
#' and another SparkDataFrame. This is equivalent to \code{UNION ALL} in SQL.
#' Input SparkDataFrames can have different schemas (names and data types).
#'
#' Note: This does not remove duplicate rows across the two SparkDataFrames.
#' Also as standard in SQL, this function resolves columns by position (not by name).
#'
#' @param x A SparkDataFrame
#' @param y A SparkDataFrame
#' @return A SparkDataFrame containing the result of the union.
#' @family SparkDataFrame functions
#' @rdname union
#' @name union
#' @aliases union,SparkDataFrame,SparkDataFrame-method
#' @seealso \link{rbind} \link{unionByName}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df1 <- read.json(path)
#' df2 <- read.json(path2)
#' unioned <- union(df, df2)
#' unions <- rbind(df, df2, df3, df4)
#' }
#' @note union since 2.0.0
setMethod("union",
signature(x = "SparkDataFrame", y = "SparkDataFrame"),
function(x, y) {
unioned <- callJMethod(x@sdf, "union", y@sdf)
dataFrame(unioned)
})
#' unionAll is deprecated - use union instead
#' @rdname union
#' @name unionAll
#' @aliases unionAll,SparkDataFrame,SparkDataFrame-method
#' @export
#' @note unionAll since 1.4.0
setMethod("unionAll",
signature(x = "SparkDataFrame", y = "SparkDataFrame"),
function(x, y) {
.Deprecated("union")
union(x, y)
})
#' Return a new SparkDataFrame containing the union of rows, matched by column names
#'
#' Return a new SparkDataFrame containing the union of rows in this SparkDataFrame
#' and another SparkDataFrame. This is different from \code{union} function, and both
#' \code{UNION ALL} and \code{UNION DISTINCT} in SQL as column positions are not taken
#' into account. Input SparkDataFrames can have different data types in the schema.
#'
#' Note: This does not remove duplicate rows across the two SparkDataFrames.
#' This function resolves columns by name (not by position).
#'
#' @param x A SparkDataFrame
#' @param y A SparkDataFrame
#' @return A SparkDataFrame containing the result of the union.
#' @family SparkDataFrame functions
#' @rdname unionByName
#' @name unionByName
#' @aliases unionByName,SparkDataFrame,SparkDataFrame-method
#' @seealso \link{rbind} \link{union}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df1 <- select(createDataFrame(mtcars), "carb", "am", "gear")
#' df2 <- select(createDataFrame(mtcars), "am", "gear", "carb")
#' head(unionByName(df1, df2))
#' }
#' @note unionByName since 2.3.0
setMethod("unionByName",
signature(x = "SparkDataFrame", y = "SparkDataFrame"),
function(x, y) {
unioned <- callJMethod(x@sdf, "unionByName", y@sdf)
dataFrame(unioned)
})
#' Union two or more SparkDataFrames
#'
#' Union two or more SparkDataFrames by row. As in R's \code{rbind}, this method
#' requires that the input SparkDataFrames have the same column names.
#'
#' Note: This does not remove duplicate rows across the two SparkDataFrames.
#'
#' @param x a SparkDataFrame.
#' @param ... additional SparkDataFrame(s).
#' @param deparse.level currently not used (put here to match the signature of
#' the base implementation).
#' @return A SparkDataFrame containing the result of the union.
#' @family SparkDataFrame functions
#' @aliases rbind,SparkDataFrame-method
#' @rdname rbind
#' @name rbind
#' @seealso \link{union} \link{unionByName}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' unions <- rbind(df, df2, df3, df4)
#' }
#' @note rbind since 1.5.0
setMethod("rbind",
signature(... = "SparkDataFrame"),
function(x, ..., deparse.level = 1) {
nm <- lapply(list(x, ...), names)
if (length(unique(nm)) != 1) {
stop("Names of input data frames are different.")
}
if (nargs() == 3) {
union(x, ...)
} else {
union(x, Recall(..., deparse.level = 1))
}
})
#' Intersect
#'
#' Return a new SparkDataFrame containing rows only in both this SparkDataFrame
#' and another SparkDataFrame. This is equivalent to \code{INTERSECT} in SQL.
#'
#' @param x A SparkDataFrame
#' @param y A SparkDataFrame
#' @return A SparkDataFrame containing the result of the intersect.
#' @family SparkDataFrame functions
#' @aliases intersect,SparkDataFrame,SparkDataFrame-method
#' @rdname intersect
#' @name intersect
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df1 <- read.json(path)
#' df2 <- read.json(path2)
#' intersectDF <- intersect(df, df2)
#' }
#' @note intersect since 1.4.0
setMethod("intersect",
signature(x = "SparkDataFrame", y = "SparkDataFrame"),
function(x, y) {
intersected <- callJMethod(x@sdf, "intersect", y@sdf)
dataFrame(intersected)
})
#' except
#'
#' Return a new SparkDataFrame containing rows in this SparkDataFrame
#' but not in another SparkDataFrame. This is equivalent to \code{EXCEPT} in SQL.
#'
#' @param x a SparkDataFrame.
#' @param y a SparkDataFrame.
#' @return A SparkDataFrame containing the result of the except operation.
#' @family SparkDataFrame functions
#' @aliases except,SparkDataFrame,SparkDataFrame-method
#' @rdname except
#' @name except
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df1 <- read.json(path)
#' df2 <- read.json(path2)
#' exceptDF <- except(df, df2)
#' }
#' @rdname except
#' @export
#' @note except since 1.4.0
setMethod("except",
signature(x = "SparkDataFrame", y = "SparkDataFrame"),
function(x, y) {
excepted <- callJMethod(x@sdf, "except", y@sdf)
dataFrame(excepted)
})
#' Save the contents of SparkDataFrame to a data source.
#'
#' The data source is specified by the \code{source} and a set of options (...).
#' If \code{source} is not specified, the default data source configured by
#' spark.sql.sources.default will be used.
#'
#' Additionally, mode is used to specify the behavior of the save operation when data already
#' exists in the data source. There are four modes:
#' \itemize{
#' \item 'append': Contents of this SparkDataFrame are expected to be appended to existing data.
#' \item 'overwrite': Existing data is expected to be overwritten by the contents of this
#' SparkDataFrame.
#' \item 'error' or 'errorifexists': An exception is expected to be thrown.
#' \item 'ignore': The save operation is expected to not save the contents of the SparkDataFrame
#' and to not change the existing data.
#' }
#'
#' @param df a SparkDataFrame.
#' @param path a name for the table.
#' @param source a name for external data source.
#' @param mode one of 'append', 'overwrite', 'error', 'errorifexists', 'ignore'
#' save mode (it is 'error' by default)
#' @param ... additional argument(s) passed to the method.
#'
#' @family SparkDataFrame functions
#' @aliases write.df,SparkDataFrame-method
#' @rdname write.df
#' @name write.df
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' write.df(df, "myfile", "parquet", "overwrite")
#' saveDF(df, parquetPath2, "parquet", mode = "append", mergeSchema = TRUE)
#' }
#' @note write.df since 1.4.0
setMethod("write.df",
signature(df = "SparkDataFrame"),
function(df, path = NULL, source = NULL, mode = "error", ...) {
if (!is.null(path) && !is.character(path)) {
stop("path should be character, NULL or omitted.")
}
if (!is.null(source) && !is.character(source)) {
stop("source should be character, NULL or omitted. It is the datasource specified ",
"in 'spark.sql.sources.default' configuration by default.")
}
if (!is.character(mode)) {
stop("mode should be character or omitted. It is 'error' by default.")
}
if (is.null(source)) {
source <- getDefaultSqlSource()
}
write <- callJMethod(df@sdf, "write")
write <- callJMethod(write, "format", source)
write <- setWriteOptions(write, path = path, mode = mode, ...)
write <- handledCallJMethod(write, "save")
})
#' @rdname write.df
#' @name saveDF
#' @aliases saveDF,SparkDataFrame,character-method
#' @export
#' @note saveDF since 1.4.0
setMethod("saveDF",
signature(df = "SparkDataFrame", path = "character"),
function(df, path, source = NULL, mode = "error", ...) {
write.df(df, path, source, mode, ...)
})
#' Save the contents of the SparkDataFrame to a data source as a table
#'
#' The data source is specified by the \code{source} and a set of options (...).
#' If \code{source} is not specified, the default data source configured by
#' spark.sql.sources.default will be used.
#'
#' Additionally, mode is used to specify the behavior of the save operation when
#' data already exists in the data source. There are four modes: \cr
#' 'append': Contents of this SparkDataFrame are expected to be appended to existing data. \cr
#' 'overwrite': Existing data is expected to be overwritten by the contents of this
#' SparkDataFrame. \cr
#' 'error' or 'errorifexists': An exception is expected to be thrown. \cr
#' 'ignore': The save operation is expected to not save the contents of the SparkDataFrame
#' and to not change the existing data. \cr
#'
#' @param df a SparkDataFrame.
#' @param tableName a name for the table.
#' @param source a name for external data source.
#' @param mode one of 'append', 'overwrite', 'error', 'errorifexists', 'ignore'
#' save mode (it is 'error' by default)
#' @param ... additional option(s) passed to the method.
#'
#' @family SparkDataFrame functions
#' @aliases saveAsTable,SparkDataFrame,character-method
#' @rdname saveAsTable
#' @name saveAsTable
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' saveAsTable(df, "myfile")
#' }
#' @note saveAsTable since 1.4.0
setMethod("saveAsTable",
signature(df = "SparkDataFrame", tableName = "character"),
function(df, tableName, source = NULL, mode="error", ...) {
if (is.null(source)) {
source <- getDefaultSqlSource()
}
options <- varargsToStrEnv(...)
write <- callJMethod(df@sdf, "write")
write <- callJMethod(write, "format", source)
write <- setWriteMode(write, mode)
write <- callJMethod(write, "options", options)
invisible(callJMethod(write, "saveAsTable", tableName))
})
#' describe
#'
#' Computes statistics for numeric and string columns.
#' If no columns are given, this function computes statistics for all numerical or string columns.
#'
#' @param x a SparkDataFrame to be computed.
#' @param col a string of name.
#' @param ... additional expressions.
#' @return A SparkDataFrame.
#' @family SparkDataFrame functions
#' @aliases describe,SparkDataFrame,character-method describe,SparkDataFrame,ANY-method
#' @rdname describe
#' @name describe
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' describe(df)
#' describe(df, "col1")
#' describe(df, "col1", "col2")
#' }
#' @seealso See \link{summary} for expanded statistics and control over which statistics to compute.
#' @note describe(SparkDataFrame, character) since 1.4.0
setMethod("describe",
signature(x = "SparkDataFrame", col = "character"),
function(x, col, ...) {
colList <- list(col, ...)
sdf <- callJMethod(x@sdf, "describe", colList)
dataFrame(sdf)
})
#' @rdname describe
#' @name describe
#' @aliases describe,SparkDataFrame-method
#' @note describe(SparkDataFrame) since 1.4.0
setMethod("describe",
signature(x = "SparkDataFrame"),
function(x) {
sdf <- callJMethod(x@sdf, "describe", list())
dataFrame(sdf)
})
#' summary
#'
#' Computes specified statistics for numeric and string columns. Available statistics are:
#' \itemize{
#' \item count
#' \item mean
#' \item stddev
#' \item min
#' \item max
#' \item arbitrary approximate percentiles specified as a percentage (eg, "75%")
#' }
#' If no statistics are given, this function computes count, mean, stddev, min,
#' approximate quartiles (percentiles at 25%, 50%, and 75%), and max.
#' This function is meant for exploratory data analysis, as we make no guarantee about the
#' backward compatibility of the schema of the resulting Dataset. If you want to
#' programmatically compute summary statistics, use the \code{agg} function instead.
#'
#'
#' @param object a SparkDataFrame to be summarized.
#' @param ... (optional) statistics to be computed for all columns.
#' @return A SparkDataFrame.
#' @family SparkDataFrame functions
#' @rdname summary
#' @name summary
#' @aliases summary,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' summary(df)
#' summary(df, "min", "25%", "75%", "max")
#' summary(select(df, "age", "height"))
#' }
#' @note summary(SparkDataFrame) since 1.5.0
#' @note The statistics provided by \code{summary} were change in 2.3.0 use \link{describe} for
#' previous defaults.
#' @seealso \link{describe}
setMethod("summary",
signature(object = "SparkDataFrame"),
function(object, ...) {
statisticsList <- list(...)
sdf <- callJMethod(object@sdf, "summary", statisticsList)
dataFrame(sdf)
})
#' A set of SparkDataFrame functions working with NA values
#'
#' dropna, na.omit - Returns a new SparkDataFrame omitting rows with null values.
#'
#' @param x a SparkDataFrame.
#' @param how "any" or "all".
#' if "any", drop a row if it contains any nulls.
#' if "all", drop a row only if all its values are null.
#' if \code{minNonNulls} is specified, how is ignored.
#' @param minNonNulls if specified, drop rows that have less than
#' \code{minNonNulls} non-null values.
#' This overwrites the how parameter.
#' @param cols optional list of column names to consider. In \code{fillna},
#' columns specified in cols that do not have matching data
#' type are ignored. For example, if value is a character, and
#' subset contains a non-character column, then the non-character
#' column is simply ignored.
#' @return A SparkDataFrame.
#'
#' @family SparkDataFrame functions
#' @rdname nafunctions
#' @aliases dropna,SparkDataFrame-method
#' @name dropna
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' dropna(df)
#' }
#' @note dropna since 1.4.0
setMethod("dropna",
signature(x = "SparkDataFrame"),
function(x, how = c("any", "all"), minNonNulls = NULL, cols = NULL) {
how <- match.arg(how)
if (is.null(cols)) {
cols <- columns(x)
}
if (is.null(minNonNulls)) {
minNonNulls <- if (how == "any") { length(cols) } else { 1 }
}
naFunctions <- callJMethod(x@sdf, "na")
sdf <- callJMethod(naFunctions, "drop",
as.integer(minNonNulls), as.list(cols))
dataFrame(sdf)
})
#' @param object a SparkDataFrame.
#' @param ... further arguments to be passed to or from other methods.
#' @rdname nafunctions
#' @name na.omit
#' @aliases na.omit,SparkDataFrame-method
#' @export
#' @note na.omit since 1.5.0
setMethod("na.omit",
signature(object = "SparkDataFrame"),
function(object, how = c("any", "all"), minNonNulls = NULL, cols = NULL) {
dropna(object, how, minNonNulls, cols)
})
#' fillna - Replace null values.
#'
#' @param value value to replace null values with.
#' Should be an integer, numeric, character or named list.
#' If the value is a named list, then cols is ignored and
#' value must be a mapping from column name (character) to
#' replacement value. The replacement value must be an
#' integer, numeric or character.
#'
#' @rdname nafunctions
#' @name fillna
#' @aliases fillna,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' fillna(df, 1)
#' fillna(df, list("age" = 20, "name" = "unknown"))
#' }
#' @note fillna since 1.4.0
setMethod("fillna",
signature(x = "SparkDataFrame"),
function(x, value, cols = NULL) {
if (!(class(value) %in% c("integer", "numeric", "character", "list"))) {
stop("value should be an integer, numeric, character or named list.")
}
if (class(value) == "list") {
# Check column names in the named list
colNames <- names(value)
if (length(colNames) == 0 || !all(colNames != "")) {
stop("value should be an a named list with each name being a column name.")
}
# Check each item in the named list is of valid type
lapply(value, function(v) {
if (!(class(v) %in% c("integer", "numeric", "character"))) {
stop("Each item in value should be an integer, numeric or character.")
}
})
# Convert to the named list to an environment to be passed to JVM
valueMap <- convertNamedListToEnv(value)
# When value is a named list, caller is expected not to pass in cols
if (!is.null(cols)) {
warning("When value is a named list, cols is ignored!")
cols <- NULL
}
value <- valueMap
} else if (is.integer(value)) {
# Cast an integer to a numeric
value <- as.numeric(value)
}
naFunctions <- callJMethod(x@sdf, "na")
sdf <- if (length(cols) == 0) {
callJMethod(naFunctions, "fill", value)
} else {
callJMethod(naFunctions, "fill", value, as.list(cols))
}
dataFrame(sdf)
})
#' Download data from a SparkDataFrame into a R data.frame
#'
#' This function downloads the contents of a SparkDataFrame into an R's data.frame.
#' Since data.frames are held in memory, ensure that you have enough memory
#' in your system to accommodate the contents.
#'
#' @param x a SparkDataFrame.
#' @param row.names \code{NULL} or a character vector giving the row names for the data frame.
#' @param optional If \code{TRUE}, converting column names is optional.
#' @param ... additional arguments to pass to base::as.data.frame.
#' @return A data.frame.
#' @family SparkDataFrame functions
#' @aliases as.data.frame,SparkDataFrame-method
#' @rdname as.data.frame
#' @examples
#' \dontrun{
#' irisDF <- createDataFrame(iris)
#' df <- as.data.frame(irisDF[irisDF$Species == "setosa", ])
#' }
#' @note as.data.frame since 1.6.0
setMethod("as.data.frame",
signature(x = "SparkDataFrame"),
function(x, row.names = NULL, optional = FALSE, ...) {
as.data.frame(collect(x), row.names, optional, ...)
})
#' Attach SparkDataFrame to R search path
#'
#' The specified SparkDataFrame is attached to the R search path. This means that
#' the SparkDataFrame is searched by R when evaluating a variable, so columns in
#' the SparkDataFrame can be accessed by simply giving their names.
#'
#' @family SparkDataFrame functions
#' @rdname attach
#' @aliases attach attach,SparkDataFrame-method
#' @param what (SparkDataFrame) The SparkDataFrame to attach
#' @param pos (integer) Specify position in search() where to attach.
#' @param name (character) Name to use for the attached SparkDataFrame. Names
#' starting with package: are reserved for library.
#' @param warn.conflicts (logical) If TRUE, warnings are printed about conflicts
#' from attaching the database, unless that SparkDataFrame contains an object
#' @examples
#' \dontrun{
#' attach(irisDf)
#' summary(Sepal_Width)
#' }
#' @seealso \link{detach}
#' @note attach since 1.6.0
setMethod("attach",
signature(what = "SparkDataFrame"),
function(what, pos = 2L, name = deparse(substitute(what), backtick = FALSE),
warn.conflicts = TRUE) {
args <- as.list(environment()) # capture all parameters - this must be the first line
newEnv <- assignNewEnv(args$what)
args$what <- newEnv
do.call(attach, args)
})
#' Evaluate a R expression in an environment constructed from a SparkDataFrame
#'
#' Evaluate a R expression in an environment constructed from a SparkDataFrame
#' with() allows access to columns of a SparkDataFrame by simply referring to
#' their name. It appends every column of a SparkDataFrame into a new
#' environment. Then, the given expression is evaluated in this new
#' environment.
#'
#' @rdname with
#' @family SparkDataFrame functions
#' @aliases with,SparkDataFrame-method
#' @param data (SparkDataFrame) SparkDataFrame to use for constructing an environment.
#' @param expr (expression) Expression to evaluate.
#' @param ... arguments to be passed to future methods.
#' @examples
#' \dontrun{
#' with(irisDf, nrow(Sepal_Width))
#' }
#' @seealso \link{attach}
#' @note with since 1.6.0
setMethod("with",
signature(data = "SparkDataFrame"),
function(data, expr, ...) {
newEnv <- assignNewEnv(data)
eval(substitute(expr), envir = newEnv, enclos = newEnv)
})
#' Compactly display the structure of a dataset
#'
#' Display the structure of a SparkDataFrame, including column names, column types, as well as a
#' a small sample of rows.
#'
#' @name str
#' @rdname str
#' @aliases str,SparkDataFrame-method
#' @family SparkDataFrame functions
#' @param object a SparkDataFrame
#' @examples
#' \dontrun{
#' # Create a SparkDataFrame from the Iris dataset
#' irisDF <- createDataFrame(iris)
#'
#' # Show the structure of the SparkDataFrame
#' str(irisDF)
#' }
#' @note str since 1.6.1
setMethod("str",
signature(object = "SparkDataFrame"),
function(object) {
# TODO: These could be made global parameters, though in R it's not the case
MAX_CHAR_PER_ROW <- 120
MAX_COLS <- 100
# Get the column names and types of the DataFrame
names <- names(object)
types <- coltypes(object)
# Get the first elements of the dataset. Limit number of columns accordingly
localDF <- if (ncol(object) > MAX_COLS) {
head(object[, c(1:MAX_COLS)])
} else {
head(object)
}
# The number of observations will not be displayed as computing the
# number of rows is a very expensive operation
cat(paste0("'", class(object), "': ", length(names), " variables:\n"))
if (nrow(localDF) > 0) {
for (i in 1 : ncol(localDF)) {
# Get the first elements for each column
firstElements <- if (types[i] == "character") {
paste(paste0("\"", localDF[, i], "\""), collapse = " ")
} else {
paste(localDF[, i], collapse = " ")
}
# Add the corresponding number of spaces for alignment
spaces <- paste(rep(" ", max(nchar(names) - nchar(names[i]))), collapse = "")
# Get the short type. For 'character', it would be 'chr';
# 'for numeric', it's 'num', etc.
dataType <- SHORT_TYPES[[types[i]]]
if (is.null(dataType)) {
dataType <- substring(types[i], 1, 3)
}
# Concatenate the colnames, coltypes, and first
# elements of each column
line <- paste0(" $ ", names[i], spaces, ": ",
dataType, " ", firstElements)
# Chop off extra characters if this is too long
cat(substr(line, 1, MAX_CHAR_PER_ROW))
cat("\n")
}
if (ncol(localDF) < ncol(object)) {
cat(paste0("\nDisplaying first ", ncol(localDF), " columns only."))
}
}
})
#' drop
#'
#' Returns a new SparkDataFrame with columns dropped.
#' This is a no-op if schema doesn't contain column name(s).
#'
#' @param x a SparkDataFrame.
#' @param col a character vector of column names or a Column.
#' @param ... further arguments to be passed to or from other methods.
#' @return A SparkDataFrame.
#'
#' @family SparkDataFrame functions
#' @rdname drop
#' @name drop
#' @aliases drop,SparkDataFrame-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' path <- "path/to/file.json"
#' df <- read.json(path)
#' drop(df, "col1")
#' drop(df, c("col1", "col2"))
#' drop(df, df$col1)
#' }
#' @note drop since 2.0.0
setMethod("drop",
signature(x = "SparkDataFrame"),
function(x, col) {
stopifnot(class(col) == "character" || class(col) == "Column")
if (class(col) == "Column") {
sdf <- callJMethod(x@sdf, "drop", col@jc)
} else {
sdf <- callJMethod(x@sdf, "drop", as.list(col))
}
dataFrame(sdf)
})
# Expose base::drop
#' @name drop
#' @rdname drop
#' @aliases drop,ANY-method
#' @export
setMethod("drop",
signature(x = "ANY"),
function(x) {
base::drop(x)
})
#' Compute histogram statistics for given column
#'
#' This function computes a histogram for a given SparkR Column.
#'
#' @name histogram
#' @param nbins the number of bins (optional). Default value is 10.
#' @param col the column as Character string or a Column to build the histogram from.
#' @param df the SparkDataFrame containing the Column to build the histogram from.
#' @return a data.frame with the histogram statistics, i.e., counts and centroids.
#' @rdname histogram
#' @aliases histogram,SparkDataFrame,characterOrColumn-method
#' @family SparkDataFrame functions
#' @export
#' @examples
#' \dontrun{
#'
#' # Create a SparkDataFrame from the Iris dataset
#' irisDF <- createDataFrame(iris)
#'
#' # Compute histogram statistics
#' histStats <- histogram(irisDF, irisDF$Sepal_Length, nbins = 12)
#'
#' # Once SparkR has computed the histogram statistics, the histogram can be
#' # rendered using the ggplot2 library:
#'
#' require(ggplot2)
#' plot <- ggplot(histStats, aes(x = centroids, y = counts)) +
#' geom_bar(stat = "identity") +
#' xlab("Sepal_Length") + ylab("Frequency")
#' }
#' @note histogram since 2.0.0
setMethod("histogram",
signature(df = "SparkDataFrame", col = "characterOrColumn"),
function(df, col, nbins = 10) {
# Validate nbins
if (nbins < 2) {
stop("The number of bins must be a positive integer number greater than 1.")
}
# Round nbins to the smallest integer
nbins <- floor(nbins)
# Validate col
if (is.null(col)) {
stop("col must be specified.")
}
colname <- col
x <- if (class(col) == "character") {
if (!colname %in% names(df)) {
stop("Specified colname does not belong to the given SparkDataFrame.")
}
# Filter NA values in the target column and remove all other columns
df <- na.omit(df[, colname, drop = F])
getColumn(df, colname)
} else if (class(col) == "Column") {
# The given column needs to be appended to the SparkDataFrame so that we can
# use method describe() to compute statistics in one single pass. The new
# column must have a name that doesn't exist in the dataset.
# To do so, we generate a random column name with more characters than the
# longest colname in the dataset, but no more than 100 (think of a UUID).
# This column name will never be visible to the user, so the name is irrelevant.
# Limiting the colname length to 100 makes debugging easier and it does
# introduce a negligible probability of collision: assuming the user has 1 million
# columns AND all of them have names 100 characters long (which is very unlikely),
# AND they run 1 billion histograms, the probability of collision will roughly be
# 1 in 4.4 x 10 ^ 96
colname <- paste(base::sample(c(letters, LETTERS),
size = min(max(nchar(colnames(df))) + 1, 100),
replace = TRUE),
collapse = "")
# Append the given column to the dataset. This is to support Columns that
# don't belong to the SparkDataFrame but are rather expressions
df <- withColumn(df, colname, col)
# Filter NA values in the target column. Cannot remove all other columns
# since given Column may be an expression on one or more existing columns
df <- na.omit(df)
col
}
stats <- collect(describe(df[, colname, drop = F]))
min <- as.numeric(stats[4, 2])
max <- as.numeric(stats[5, 2])
# Normalize the data
xnorm <- (x - min) / (max - min)
# Round the data to 4 significant digits. This is to avoid rounding issues.
xnorm <- cast(xnorm * 10000, "integer") / 10000.0
# Since min = 0, max = 1 (data is already normalized)
normBinSize <- 1 / nbins
binsize <- (max - min) / nbins
approxBins <- xnorm / normBinSize
# Adjust values that are equal to the upper bound of each bin
bins <- cast(approxBins -
ifelse(approxBins == cast(approxBins, "integer") & x != min, 1, 0),
"integer")
df$bins <- bins
histStats <- collect(count(groupBy(df, "bins")))
names(histStats) <- c("bins", "counts")
# Fill bins with zero counts
y <- data.frame("bins" = seq(0, nbins - 1))
histStats <- merge(histStats, y, all.x = T, all.y = T)
histStats[is.na(histStats$count), 2] <- 0
# Compute centroids
histStats$centroids <- histStats$bins * binsize + min + binsize / 2
# Return the statistics
return(histStats)
})
#' Save the content of SparkDataFrame to an external database table via JDBC.
#'
#' Save the content of the SparkDataFrame to an external database table via JDBC. Additional JDBC
#' database connection properties can be set (...)
#'
#' Also, mode is used to specify the behavior of the save operation when
#' data already exists in the data source. There are four modes:
#' \itemize{
#' \item 'append': Contents of this SparkDataFrame are expected to be appended to existing data.
#' \item 'overwrite': Existing data is expected to be overwritten by the contents of this
#' SparkDataFrame.
#' \item 'error' or 'errorifexists': An exception is expected to be thrown.
#' \item 'ignore': The save operation is expected to not save the contents of the SparkDataFrame
#' and to not change the existing data.
#' }
#'
#' @param x a SparkDataFrame.
#' @param url JDBC database url of the form \code{jdbc:subprotocol:subname}.
#' @param tableName yhe name of the table in the external database.
#' @param mode one of 'append', 'overwrite', 'error', 'errorifexists', 'ignore'
#' save mode (it is 'error' by default)
#' @param ... additional JDBC database connection properties.
#' @family SparkDataFrame functions
#' @rdname write.jdbc
#' @name write.jdbc
#' @aliases write.jdbc,SparkDataFrame,character,character-method
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' jdbcUrl <- "jdbc:mysql://localhost:3306/databasename"
#' write.jdbc(df, jdbcUrl, "table", user = "username", password = "password")
#' }
#' @note write.jdbc since 2.0.0
setMethod("write.jdbc",
signature(x = "SparkDataFrame", url = "character", tableName = "character"),
function(x, url, tableName, mode = "error", ...) {
jprops <- varargsToJProperties(...)
write <- callJMethod(x@sdf, "write")
write <- setWriteMode(write, mode)
invisible(handledCallJMethod(write, "jdbc", url, tableName, jprops))
})
#' randomSplit
#'
#' Return a list of randomly split dataframes with the provided weights.
#'
#' @param x A SparkDataFrame
#' @param weights A vector of weights for splits, will be normalized if they don't sum to 1
#' @param seed A seed to use for random split
#'
#' @family SparkDataFrame functions
#' @aliases randomSplit,SparkDataFrame,numeric-method
#' @rdname randomSplit
#' @name randomSplit
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df <- createDataFrame(data.frame(id = 1:1000))
#' df_list <- randomSplit(df, c(2, 3, 5), 0)
#' # df_list contains 3 SparkDataFrames with each having about 200, 300 and 500 rows respectively
#' sapply(df_list, count)
#' }
#' @note randomSplit since 2.0.0
setMethod("randomSplit",
signature(x = "SparkDataFrame", weights = "numeric"),
function(x, weights, seed) {
if (!all(sapply(weights, function(c) { c >= 0 }))) {
stop("all weight values should not be negative")
}
normalized_list <- as.list(weights / sum(weights))
if (!missing(seed)) {
sdfs <- callJMethod(x@sdf, "randomSplit", normalized_list, as.integer(seed))
} else {
sdfs <- callJMethod(x@sdf, "randomSplit", normalized_list)
}
sapply(sdfs, dataFrame)
})
#' getNumPartitions
#'
#' Return the number of partitions
#'
#' @param x A SparkDataFrame
#' @family SparkDataFrame functions
#' @aliases getNumPartitions,SparkDataFrame-method
#' @rdname getNumPartitions
#' @name getNumPartitions
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df <- createDataFrame(cars, numPartitions = 2)
#' getNumPartitions(df)
#' }
#' @note getNumPartitions since 2.1.1
setMethod("getNumPartitions",
signature(x = "SparkDataFrame"),
function(x) {
callJMethod(callJMethod(x@sdf, "rdd"), "getNumPartitions")
})
#' isStreaming
#'
#' Returns TRUE if this SparkDataFrame contains one or more sources that continuously return data
#' as it arrives.
#'
#' @param x A SparkDataFrame
#' @return TRUE if this SparkDataFrame is from a streaming source
#' @family SparkDataFrame functions
#' @aliases isStreaming,SparkDataFrame-method
#' @rdname isStreaming
#' @name isStreaming
#' @seealso \link{read.stream} \link{write.stream}
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df <- read.stream("socket", host = "localhost", port = 9999)
#' isStreaming(df)
#' }
#' @note isStreaming since 2.2.0
#' @note experimental
setMethod("isStreaming",
signature(x = "SparkDataFrame"),
function(x) {
callJMethod(x@sdf, "isStreaming")
})
#' Write the streaming SparkDataFrame to a data source.
#'
#' The data source is specified by the \code{source} and a set of options (...).
#' If \code{source} is not specified, the default data source configured by
#' spark.sql.sources.default will be used.
#'
#' Additionally, \code{outputMode} specifies how data of a streaming SparkDataFrame is written to a
#' output data source. There are three modes:
#' \itemize{
#' \item append: Only the new rows in the streaming SparkDataFrame will be written out. This
#' output mode can be only be used in queries that do not contain any aggregation.
#' \item complete: All the rows in the streaming SparkDataFrame will be written out every time
#' there are some updates. This output mode can only be used in queries that
#' contain aggregations.
#' \item update: Only the rows that were updated in the streaming SparkDataFrame will be written
#' out every time there are some updates. If the query doesn't contain aggregations,
#' it will be equivalent to \code{append} mode.
#' }
#'
#' @param df a streaming SparkDataFrame.
#' @param source a name for external data source.
#' @param outputMode one of 'append', 'complete', 'update'.
#' @param ... additional argument(s) passed to the method.
#'
#' @family SparkDataFrame functions
#' @seealso \link{read.stream}
#' @aliases write.stream,SparkDataFrame-method
#' @rdname write.stream
#' @name write.stream
#' @export
#' @examples
#'\dontrun{
#' sparkR.session()
#' df <- read.stream("socket", host = "localhost", port = 9999)
#' isStreaming(df)
#' wordCounts <- count(group_by(df, "value"))
#'
#' # console
#' q <- write.stream(wordCounts, "console", outputMode = "complete")
#' # text stream
#' q <- write.stream(df, "text", path = "/home/user/out", checkpointLocation = "/home/user/cp")
#' # memory stream
#' q <- write.stream(wordCounts, "memory", queryName = "outs", outputMode = "complete")
#' head(sql("SELECT * from outs"))
#' queryName(q)
#'
#' stopQuery(q)
#' }
#' @note write.stream since 2.2.0
#' @note experimental
setMethod("write.stream",
signature(df = "SparkDataFrame"),
function(df, source = NULL, outputMode = NULL, ...) {
if (!is.null(source) && !is.character(source)) {
stop("source should be character, NULL or omitted. It is the data source specified ",
"in 'spark.sql.sources.default' configuration by default.")
}
if (!is.null(outputMode) && !is.character(outputMode)) {
stop("outputMode should be character or omitted.")
}
if (is.null(source)) {
source <- getDefaultSqlSource()
}
options <- varargsToStrEnv(...)
write <- handledCallJMethod(df@sdf, "writeStream")
write <- callJMethod(write, "format", source)
if (!is.null(outputMode)) {
write <- callJMethod(write, "outputMode", outputMode)
}
write <- callJMethod(write, "options", options)
ssq <- handledCallJMethod(write, "start")
streamingQuery(ssq)
})
#' checkpoint
#'
#' Returns a checkpointed version of this SparkDataFrame. Checkpointing can be used to truncate the
#' logical plan, which is especially useful in iterative algorithms where the plan may grow
#' exponentially. It will be saved to files inside the checkpoint directory set with
#' \code{setCheckpointDir}
#'
#' @param x A SparkDataFrame
#' @param eager whether to checkpoint this SparkDataFrame immediately
#' @return a new checkpointed SparkDataFrame
#' @family SparkDataFrame functions
#' @aliases checkpoint,SparkDataFrame-method
#' @rdname checkpoint
#' @name checkpoint
#' @seealso \link{setCheckpointDir}
#' @export
#' @examples
#'\dontrun{
#' setCheckpointDir("/checkpoint")
#' df <- checkpoint(df)
#' }
#' @note checkpoint since 2.2.0
setMethod("checkpoint",
signature(x = "SparkDataFrame"),
function(x, eager = TRUE) {
df <- callJMethod(x@sdf, "checkpoint", as.logical(eager))
dataFrame(df)
})
#' cube
#'
#' Create a multi-dimensional cube for the SparkDataFrame using the specified columns.
#'
#' If grouping expression is missing \code{cube} creates a single global aggregate and is
#' equivalent to direct application of \link{agg}.
#'
#' @param x a SparkDataFrame.
#' @param ... character name(s) or Column(s) to group on.
#' @return A GroupedData.
#' @family SparkDataFrame functions
#' @aliases cube,SparkDataFrame-method
#' @rdname cube
#' @name cube
#' @export
#' @examples
#' \dontrun{
#' df <- createDataFrame(mtcars)
#' mean(cube(df, "cyl", "gear", "am"), "mpg")
#'
#' # Following calls are equivalent
#' agg(cube(df), mean(df$mpg))
#' agg(df, mean(df$mpg))
#' }
#' @note cube since 2.3.0
#' @seealso \link{agg}, \link{groupBy}, \link{rollup}
setMethod("cube",
signature(x = "SparkDataFrame"),
function(x, ...) {
cols <- list(...)
jcol <- lapply(cols, function(x) if (class(x) == "Column") x@jc else column(x)@jc)
sgd <- callJMethod(x@sdf, "cube", jcol)
groupedData(sgd)
})
#' rollup
#'
#' Create a multi-dimensional rollup for the SparkDataFrame using the specified columns.
#'
#' If grouping expression is missing \code{rollup} creates a single global aggregate and is
#' equivalent to direct application of \link{agg}.
#'
#' @param x a SparkDataFrame.
#' @param ... character name(s) or Column(s) to group on.
#' @return A GroupedData.
#' @family SparkDataFrame functions
#' @aliases rollup,SparkDataFrame-method
#' @rdname rollup
#' @name rollup
#' @export
#' @examples
#'\dontrun{
#' df <- createDataFrame(mtcars)
#' mean(rollup(df, "cyl", "gear", "am"), "mpg")
#'
#' # Following calls are equivalent
#' agg(rollup(df), mean(df$mpg))
#' agg(df, mean(df$mpg))
#' }
#' @note rollup since 2.3.0
#' @seealso \link{agg}, \link{cube}, \link{groupBy}
setMethod("rollup",
signature(x = "SparkDataFrame"),
function(x, ...) {
cols <- list(...)
jcol <- lapply(cols, function(x) if (class(x) == "Column") x@jc else column(x)@jc)
sgd <- callJMethod(x@sdf, "rollup", jcol)
groupedData(sgd)
})
#' hint
#'
#' Specifies execution plan hint and return a new SparkDataFrame.
#'
#' @param x a SparkDataFrame.
#' @param name a name of the hint.
#' @param ... optional parameters for the hint.
#' @return A SparkDataFrame.
#' @family SparkDataFrame functions
#' @aliases hint,SparkDataFrame,character-method
#' @rdname hint
#' @name hint
#' @export
#' @examples
#' \dontrun{
#' df <- createDataFrame(mtcars)
#' avg_mpg <- mean(groupBy(createDataFrame(mtcars), "cyl"), "mpg")
#'
#' head(join(df, hint(avg_mpg, "broadcast"), df$cyl == avg_mpg$cyl))
#' }
#' @note hint since 2.2.0
setMethod("hint",
signature(x = "SparkDataFrame", name = "character"),
function(x, name, ...) {
parameters <- list(...)
stopifnot(all(sapply(parameters, is.character)))
jdf <- callJMethod(x@sdf, "hint", name, parameters)
dataFrame(jdf)
})
#' alias
#'
#' @aliases alias,SparkDataFrame-method
#' @family SparkDataFrame functions
#' @rdname alias
#' @name alias
#' @export
#' @examples
#' \dontrun{
#' df <- alias(createDataFrame(mtcars), "mtcars")
#' avg_mpg <- alias(agg(groupBy(df, df$cyl), avg(df$mpg)), "avg_mpg")
#'
#' head(select(df, column("mtcars.mpg")))
#' head(join(df, avg_mpg, column("mtcars.cyl") == column("avg_mpg.cyl")))
#' }
#' @note alias(SparkDataFrame) since 2.3.0
setMethod("alias",
signature(object = "SparkDataFrame"),
function(object, data) {
stopifnot(is.character(data))
sdf <- callJMethod(object@sdf, "alias", data)
dataFrame(sdf)
})
#' broadcast
#'
#' Return a new SparkDataFrame marked as small enough for use in broadcast joins.
#'
#' Equivalent to \code{hint(x, "broadcast")}.
#'
#' @param x a SparkDataFrame.
#' @return a SparkDataFrame.
#'
#' @aliases broadcast,SparkDataFrame-method
#' @family SparkDataFrame functions
#' @rdname broadcast
#' @name broadcast
#' @export
#' @examples
#' \dontrun{
#' df <- createDataFrame(mtcars)
#' avg_mpg <- mean(groupBy(createDataFrame(mtcars), "cyl"), "mpg")
#'
#' head(join(df, broadcast(avg_mpg), df$cyl == avg_mpg$cyl))
#' }
#' @note broadcast since 2.3.0
setMethod("broadcast",
signature(x = "SparkDataFrame"),
function(x) {
sdf <- callJStatic("org.apache.spark.sql.functions", "broadcast", x@sdf)
dataFrame(sdf)
})
R Package Documentation
Browse R Packages
We want your feedback!
Note that we can't provide technical support on individual packages. You should contact the package authors for that.
Embedding an R snippet on your website
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.