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https://issues.apache.org/jira/browse/SPARK-9744?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sean Owen updated SPARK-9744:
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Priority: Minor (was: Major)
This sounds a bit like a windowing function. This is something you can do with
a zip-with-index and join -- does that not work?
Or you can get the same effect efficiently* with mapPartitions, and using Scala
collections methods to look at pairs of elements at a time. This also depends
on the elements being sorted.
*you'd fail to compare elements across partition boundaries; sometimes that is
a non-starter, sometimes that's fine.
> Add Java RDD method to map with lag and lead
> --------------------------------------------
>
> Key: SPARK-9744
> URL: https://issues.apache.org/jira/browse/SPARK-9744
> Project: Spark
> Issue Type: Wish
> Reporter: Jerry Z
> Priority: Minor
>
> To avoid zipping with index and doing numerous mapping and joins, having a
> single method call to map with an additional two parameters (1: list of
> offsets [(-) for lag, 0 for current and (+) for lead])) and (2:default
> value). The other difference to the map function takes an argument of List<T>
> and not just T.
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