#' Make a rename columns node (not a relational operation).
#'
#' @param source source to rename from.
#' @param cmap map written as new column names as keys and old column names as values.
#' @return rename columns node.
#'
#' @examples
#'
#' my_db <- DBI::dbConnect(RSQLite::SQLite(), ":memory:")
#' d <- dbi_copy_to(my_db, 'd',
#' data.frame(AUC = 0.6, R2 = 0.2, z = 3))
#' eqn <- rename_columns(d, c('AUC2' := 'AUC', 'R' := 'R2'))
#' cat(format(eqn))
#' sql <- to_sql(eqn, my_db)
#' cat(sql)
#' DBI::dbGetQuery(my_db, sql)
#' DBI::dbDisconnect(my_db)
#'
#' @export
#'
rename_columns <- function(source, cmap) {
if(length(cmap)<=0) {
stop("rquery::rename_columns must rename at least 1 column")
}
if(length(cmap)!=length(unique(as.character(cmap)))) {
stop("rquery::rename_columns map values must be unique")
}
if(length(cmap)!=length(unique(names(cmap)))) {
stop("rquery::rename_columns map keys must be unique")
}
have <- column_names(source)
check_have_cols(have, as.character(cmap), "rquery::rename_columns cmap")
collisions <- intersect(names(cmap), have)
if(length(collisions)>0) {
stop(paste("rquery::rename_columns rename collisions",
paste(collisions, collapse = ", ")))
}
r <- list(source = list(source),
table_name = NULL,
parsed = NULL,
cmap = cmap)
r <- relop_decorate("relop_rename_columns", r)
r
}
#' @export
column_names.relop_rename_columns <- function (x, ...) {
if(length(list(...))>0) {
stop("unexpected arguemnts")
}
sc <- column_names(x$source[[1]])
rmap <- names(x$cmap)
names(rmap) <- as.character(x$cmap)
sc[sc %in% names(rmap)] <- rmap[sc[sc %in% names(rmap)]]
sc
}
#' @export
format.relop_rename_columns <- function(x, ...) {
if(length(list(...))>0) {
stop("unexpected arguemnts")
}
paste0(trimws(format(x$source[[1]]), which = "right"),
" %.>%\n ",
"rename(.,\n",
" ", gsub("\n", "\n ",
wrapr::map_to_char(x$cmap),
fixed = TRUE), ")",
"\n")
}
calc_used_relop_rename_columns <- function (x, ...,
using = NULL,
contract = FALSE) {
cols <- column_names(x)
if(length(using)>0) {
missing <- setdiff(using, cols)
if(length(missing)>0) {
stop(paste("rquery::calc_used_relop_rename_columns unknown columns",
paste(missing, collapse = ", ")))
}
cols <- intersect(cols, using)
}
# map back prior to rename
rmap <- x$cmap
sc <- cols
sc[sc %in% names(rmap)] <- rmap[sc[sc %in% names(rmap)]]
names(sc) <- cols
sc
}
#' @export
columns_used.relop_rename_columns <- function (x, ...,
using = NULL,
contract = FALSE) {
qmap <- calc_used_relop_rename_columns(x, using=using, contract=contract)
return(columns_used(x$source[[1]],
using = as.character(qmap),
contract = contract))
}
#' @export
to_sql.relop_rename_columns <- function (x,
db,
...,
source_limit = NULL,
indent_level = 0,
tnum = mkTempNameGenerator('tsql'),
append_cr = TRUE,
using = NULL) {
if(length(list(...))>0) {
stop("unexpected arguemnts")
}
qmap <- calc_used_relop_rename_columns(x, using=using)
colsV <- vapply(as.character(qmap),
function(ci) {
quote_identifier(db, ci)
}, character(1))
colsA <- vapply(names(qmap),
function(ci) {
quote_identifier(db, ci)
}, character(1))
cols <- paste(colsV, "AS", colsA)
subsql <- to_sql(x$source[[1]],
db = db,
source_limit = source_limit,
indent_level = indent_level + 1,
tnum = tnum,
append_cr = FALSE,
using = as.character(qmap))
tab <- tnum()
prefix <- paste(rep(' ', indent_level), collapse = '')
q <- paste0(prefix, "SELECT\n",
prefix, " ", paste(cols, collapse = paste0(",\n", prefix, " ")), "\n",
prefix, "FROM (\n",
subsql, "\n",
prefix, ") ",
tab)
if(append_cr) {
q <- paste0(q, "\n")
}
q
}
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.