sdf_unnest_longer: Unnest longer

In rstudio/sparklyr: R Interface to Apache Spark

Unnest longer

Description

Expand a struct column or an array column within a Spark dataframe into one or more rows, similar what to tidyr::unnest_longer does to an R dataframe. An index column, if included, will be 1-based if 'col' is an array column.

Usage

sdf_unnest_longer(
  data,
  col,
  values_to = NULL,
  indices_to = NULL,
  include_indices = NULL,
  names_repair = "check_unique",
  ptype = list(),
  transform = list()
)

Arguments

data	The Spark dataframe to be unnested
col	The struct column to extract components from
values_to	Name of column to store vector values. Defaults to 'col'.
indices_to	A string giving the name of column which will contain the inner names or position (if not named) of the values. Defaults to 'col' with '_id' suffix
include_indices	Whether to include an index column. An index column will be included by default if 'col' is a struct column. It will also be included if 'indices_to' is not 'NULL'.
names_repair	Strategy for fixing duplicate column names (the semantic will be exactly identical to that of '.name_repair' option in tibble)
ptype	Optionally, supply an R data frame prototype for the output. Each column of the unnested result will be casted based on the Spark equivalent of the type of the column with the same name within 'ptype', e.g., if 'ptype' has a column 'x' of type 'character', then column 'x' of the unnested result will be casted from its original SQL type to StringType.
transform	Optionally, a named list of transformation functions applied

Examples

## Not run: 
library(sparklyr)
sc <- spark_connect(master = "local", version = "2.4.0")

# unnesting a struct column
sdf <- copy_to(
  sc,
  dplyr::tibble(
    x = 1:3,
    y = list(list(a = 1, b = 2), list(a = 3, b = 4), list(a = 5, b = 6))
  )
)

unnested <- sdf %>% sdf_unnest_longer(y, indices_to = "attr")

# unnesting an array column
sdf <- copy_to(
  sc,
  dplyr::tibble(
    x = 1:3,
    y = list(1:10, 1:5, 1:2)
  )
)

unnested <- sdf %>% sdf_unnest_longer(y, indices_to = "array_idx")

## End(Not run)

rstudio/sparklyr documentation built on Sept. 18, 2024, 6:10 a.m.