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https://issues.apache.org/jira/browse/MAHOUT-165?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Shashikant Kore updated MAHOUT-165:
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Attachment: mahout-165-18nov-updated.patch
I am updating the patch to ensure hashCode() is evaluated correctly. Since
hashCode() needs elements in sorted order and many other routines are OK with
any order, I have added an extra method to return iterator with sorted
elements. Only SparseVector handles the sorting flag.
This is built on Drew's patch. So, the namespaces are changed from colt to
org.apache.mahout.colt.*
> 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
> Assignee: Grant Ingersoll
> Fix For: 0.3
>
> Attachments: colt.jar, mahout-165-18nov-updated.patch,
> mahout-165-18nov.patch, mahout-165-trove.patch, MAHOUT-165-updated.patch,
> MAHOUT-165-with-colt-module.patch, MAHOUT-165-with-colt.patch,
> mahout-165.patch, MAHOUT-165.patch, 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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