Github user yanboliang commented on a diff in the pull request:
https://github.com/apache/spark/pull/11267#discussion_r53583948
--- Diff: R/pkg/R/functions.R ---
@@ -536,15 +536,27 @@ setMethod("factorial",
#'
#' Aggregate function: returns the first value in a group.
#'
+#' The function by default returns the first values it sees. It will
return the first non-NA
+#' value it sees when ignoreNAs is set to true. If all values are NA, then
NA is returned.
+#'
#' @rdname first
#' @name first
#' @family agg_funcs
#' @export
-#' @examples \dontrun{first(df$c)}
+#' @examples
+#' \dontrun{
+#' first(df$c)
+#' first(df$c, TRUE)
+#' }
setMethod("first",
- signature(x = "Column"),
- function(x) {
- jc <- callJStatic("org.apache.spark.sql.functions", "first",
x@jc)
+ signature(x = "characterOrColumn"),
+ function(x, ignoreNAs = FALSE) {
--- End diff --
Make sense, I will update. Thanks!
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