Github user NarineK commented on a diff in the pull request:
https://github.com/apache/spark/pull/12966#discussion_r62400077
--- Diff: R/pkg/R/DataFrame.R ---
@@ -1214,6 +1214,77 @@ setMethod("dapply",
dataFrame(sdf)
})
+#' gapply
+#'
+#' Apply a function to each group of a DataFrame. The group is defined by
an input
+#' grouping column(s).
+#'
+#' @param x A SparkDataFrame
+#' @param func A function to be applied to each group partition specified
by grouping
+#' column(s) of the SparkDataFrame.
+#' The output of func is a local R data.frame.
+#' @param schema The schema of the resulting SparkDataFrame after the
function is applied.
+#' It must match the output of func.
+#' @family SparkDataFrame functions
+#' @rdname gapply
+#' @name gapply
+#' @export
+#' @examples
+#'
+#' \dontrun{
+#'
+#' Computes the arithmetic mean of `Sepal_Width` by grouping
+#' on `Species`. Output the grouping value and the average.
+#'
+#' df <- createDataFrame (sqlContext, iris)
+#' schema <- structType(structField("Species", "string"),
structField("Avg", "double"))
+#' df1 <- gapply(
+#' df,
+#' function(x) {
+#' data.frame(x$Species[1], mean(x$Sepal_Width), stringsAsFactors =
FALSE)
+#' },
+#' schema, col=df$"Species")
+#' collect(df1)
+#'
+#' Species Avg
+#' -----------------
+#' virginica 2.974
+#' versicolor 2.770
+#' setosa 3.428
+#'
+#' Fits linear models on iris dataset by grouping on the `Species` column
and
+#' using `Sepal_Length` as a target variable, `Sepal_Width`, `Petal_Length`
+#' and `Petal_Width` as training features.
+#'
+#' df <- createDataFrame (sqlContext, iris)
+#' schema <- structType(structField("(Intercept)", "double"),
+#' structField("Sepal_Width", "double"), structField("Petal_Length",
"double"),
+#' structField("Petal_Width", "double"))
+#' df1 <- gapply(
+#' df,
+#' function(x) {
+#' model <- suppressWarnings(lm(Sepal_Length ~
+#' Sepal_Width + Petal_Length + Petal_Width, x))
+#' data.frame(t(coef(model)))
+#' }, schema, df$"Species")
+#' 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
+#'
+#'}
+setMethod("gapply",
+ signature(x = "SparkDataFrame", func = "function", schema =
"structType",
+ col = "Column"),
--- End diff --
yes, absolutely!
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
