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https://issues.apache.org/jira/browse/CRUNCH-57?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kiyan Ahmadizadeh updated CRUNCH-57:
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Attachment: CRUNCH-57.patch
This patch gives an implementation. A static length() method is added to
Aggregate.java and used from PCollectionImpl and MemCollection to implement a
length() function defined in the PCollection interface. The implementation for
Aggregate#length closely follows the implementation of Aggregate#count with a
few tweaks.
This functionality is exposed in Scala by adding a length function to trait
PCollectionLike.
Integration tests are added for this functionality.
> Add a length function to PCollection
> ------------------------------------
>
> Key: CRUNCH-57
> URL: https://issues.apache.org/jira/browse/CRUNCH-57
> Project: Crunch
> Issue Type: New Feature
> Components: Core
> Affects Versions: 0.3.0
> Reporter: Kiyan Ahmadizadeh
> Assignee: Josh Wills
> Attachments: CRUNCH-57.patch
>
>
> Sometimes it's useful and interesting to compute the number of elements in a
> PCollection.
>
> For example, suppose there was an initial PCollection that was then filtered
> into another. If I'm interested in how many elements of the original
> PCollection matched the filter, I'll have to write extra code to compute this.
> PCollections should have a length method that, when called, computes the
> number of elements in the PCollection and returns the result.
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