Github user actuaryzhang commented on a diff in the pull request:
https://github.com/apache/spark/pull/18422#discussion_r124719080
--- Diff: R/pkg/R/functions.R ---
@@ -2819,20 +2775,26 @@ setMethod("unix_timestamp", signature(x = "Column",
format = "character"),
jc <- callJStatic("org.apache.spark.sql.functions",
"unix_timestamp", x@jc, format)
column(jc)
})
-#' when
-#'
-#' Evaluates a list of conditions and returns one of multiple possible
result expressions.
+
+#' @details
+#' \code{when}: Evaluates a list of conditions and returns one of multiple
possible result expressions.
#' For unmatched expressions null is returned.
#'
+#' @rdname column_nonaggregate_functions
#' @param condition the condition to test on. Must be a Column expression.
#' @param value result expression.
-#' @family non-aggregate functions
-#' @rdname when
-#' @name when
-#' @aliases when,Column-method
-#' @seealso \link{ifelse}
+#' @aliases when when,Column-method
#' @export
-#' @examples \dontrun{when(df$age == 2, df$age + 1)}
+#' @examples
+#'
+#' \dontrun{
+#' tmp <- mutate(df, mpg_na = otherwise(when(df$mpg > 20, df$mpg),
lit(NaN)),
+#' mpg2 = ifelse(df$mpg > 20 & df$am > 0, 0, 1),
+#' mpg3 = ifelse(df$mpg > 20, df$mpg, 20.0))
+#' head(tmp)
+#' tmp <- mutate(tmp, ind_na1 = is.nan(tmp$mpg_na), ind_na2 =
isnan(tmp$mpg_na))
+#' head(select(tmp, coalesce(tmp$mpg_na, tmp$mpg)))
+#' head(select(tmp, nanvl(tmp$mpg_na, tmp$hp)))}
--- End diff --
@felixcheung Examples for `coalesce` and `nanvl` are here.
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