[jira] [Reopened] (SPARK-9746) PairRDDFunctions.countByKey: values/counts always 1

["Andreas (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SPARK-9746?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andreas reopened SPARK-9746:
----------------------------

Sorry, but I don't agree.

cntxt..parallelize(List (("a", 1), ("a", 2))).groupBy(_._1).countByKey()

returns 'Map(a -> 1)' but should in my opinion return 'Map(a -> 2)'

If the values (counts) are irrelevant then why this function is called *count*ByKey and why does it return a Map instead of a Set?
The current implementation has no added value compared to 'pairRDD.keys.collect().toSet'

cntxt.paralize

> PairRDDFunctions.countByKey: values/counts always 1
> ---------------------------------------------------
>
>                 Key: SPARK-9746
>                 URL: https://issues.apache.org/jira/browse/SPARK-9746
>             Project: Spark
>          Issue Type: Bug
>          Components: Spark Core
>    Affects Versions: 1.4.0
>            Reporter: Andreas
>
> org.apache.spark.rdd.PairRDDFunctionscountByKey(): Map[K, Long] = self.withScope {
>     self.mapValues(_ => 1L).reduceByKey(_ + _).collect().toMap
>   }
> obviously always returns count 1 for each key.
> If I understand the docs correctly I would expect this implementation:
> self.mapValues(_.size).reduceByKey(_ + _).collect().toMap



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