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From "Sean Owen (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MAHOUT-165) Using better primitives hash for sparse vector for performance gains
Date Thu, 20 Aug 2009 12:25:15 GMT

    [ https://issues.apache.org/jira/browse/MAHOUT-165?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12745422#action_12745422
] 

Sean Owen commented on MAHOUT-165:
----------------------------------

Yes, surely we can simply repackage the .jar to not even include those classes and redistribute
only that part which we use and can license.
Or as you say merely reuse the source.

> Using better primitives hash for sparse vector for performance gains
> --------------------------------------------------------------------
>
>                 Key: MAHOUT-165
>                 URL: https://issues.apache.org/jira/browse/MAHOUT-165
>             Project: Mahout
>          Issue Type: Improvement
>          Components: Matrix
>    Affects Versions: 0.2
>            Reporter: Shashikant Kore
>             Fix For: 0.2
>
>         Attachments: mahout-165.patch
>
>
> In SparseVector, we need primitives hash map for index and values. The present implementation
of this hash map is not as efficient as some of the other implementations in non-Apache projects.

> In an experiment, I found that, for get/set operations, the primitive hash of  Colt performance
an order of magnitude better than OrderedIntDoubleMapping. For iteration it is 2x slower,
though. 
> Using Colt in Sparsevector improved performance of canopy generation. For an experimental
dataset, the current implementation takes 50 minutes. Using Colt, reduces this duration to
19-20 minutes. That's 60% reduction in the delay. 

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