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https://issues.apache.org/jira/browse/MAHOUT-963?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13195599#comment-13195599
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Sean Owen commented on MAHOUT-963:
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I think something else must be at work... I just don't see how sorting 20
things can take more time than it does to, say, read them into memory from disk
and construct an object around them. It can't be 90+% of the time. But in any
event it is a good change.
Some similarity implementations depend on them being ordered by user or item,
to do an efficient intersection.
> GenericUserPreferenceArray and GenericItemPreferenceArray use selection sorts
> -----------------------------------------------------------------------------
>
> Key: MAHOUT-963
> URL: https://issues.apache.org/jira/browse/MAHOUT-963
> Project: Mahout
> Issue Type: Improvement
> Components: Collaborative Filtering
> Affects Versions: 0.6
> Reporter: Bryce Nyeggen
> Assignee: Sean Owen
> Priority: Minor
> Attachments: MAHOUT-963.diff
>
> Original Estimate: 1h
> Remaining Estimate: 1h
>
> Both PreferenceArray implementations use selection sorts with poor
> performance. These sorts are invoked during construction of
> GenericDataModels, causing excessive construction time.
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