[ https://issues.apache.org/jira/browse/SPARK-12922?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Apache Spark reassigned SPARK-12922:
------------------------------------
Assignee: (was: Apache Spark)
> Implement gapply() on DataFrame in SparkR
> -----------------------------------------
>
> Key: SPARK-12922
> URL: https://issues.apache.org/jira/browse/SPARK-12922
> Project: Spark
> Issue Type: Sub-task
> Components: SparkR
> Affects Versions: 1.6.0
> Reporter: Sun Rui
>
> gapply() applies an R function on groups grouped by one or more columns of a DataFrame,
and returns a DataFrame. It is like GroupedDataSet.flatMapGroups() in the Dataset API.
> Two API styles are supported:
> 1.
> {code}
> gd <- groupBy(df, col1, ...)
> gapply(gd, function(grouping_key, group) {}, schema)
> {code}
> 2.
> {code}
> gapply(df, grouping_columns, function(grouping_key, group) {}, schema)
> {code}
> R function input: grouping keys value, a local data.frame of this grouped data
> R function output: local data.frame
> Schema specifies the Row format of the output of the R function. It must match the R
function's output.
> Note that map-side combination (partial aggregation) is not supported, user could do
map-side combination via dapply().
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