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Posted to issues@spark.apache.org by "Hyukjin Kwon (Jira)" <ji...@apache.org> on 2019/08/23 09:32:00 UTC
[jira] [Issue Comment Deleted] (SPARK-28854) Zipping iterators in
mapPartitions will fail
[ https://issues.apache.org/jira/browse/SPARK-28854?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Hyukjin Kwon updated SPARK-28854:
---------------------------------
Comment: was deleted
(was: Your {{xs.map(2*)}} produces:
{code}
scala> sc.parallelize(Seq(1, 2, 3)).mapPartitions(xs => xs.map(2*)).collect.foreach(println)
2
4
6
{code}
So, it cannot be zipped. {{zip}} in your codes is Scala library, not Spark.)
> Zipping iterators in mapPartitions will fail
> --------------------------------------------
>
> Key: SPARK-28854
> URL: https://issues.apache.org/jira/browse/SPARK-28854
> Project: Spark
> Issue Type: Bug
> Components: Spark Core
> Affects Versions: 2.4.3
> Reporter: Hao Yang Ang
> Priority: Minor
>
> scala> sc.parallelize(Seq(1, 2, 3)).mapPartitions(xs => xs.map(2*).zip(xs)).collect.foreach(println)
> warning: there was one feature warning; re-run with -feature for details
> 19/08/22 21:13:18 ERROR Executor: Exception in task 1.0 in stage 0.0 (TID 1)
> java.util.NoSuchElementException: next on empty iterator
>
>
> Workaround - implement zip with mapping to tuple:
> scala> sc.parallelize(Seq(1, 2, 3)).mapPartitions(xs => xs.map(x => (x * 2, x))).collect.foreach(println)
> (2,1)
> (4,2)
> (6,3)
>
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