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https://issues.apache.org/jira/browse/MAHOUT-165?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12760956#action_12760956
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Sean Owen commented on MAHOUT-165:
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Are my conclusions sound then:
We agree that equals() should be 'pretty strict'. The conventional Java wisdom
is that equals(), in fact, ought not return true for instances of differing
classes, unless you really know what you're doing. I guess we do. :)
If the idea behind equals() is "do class-specific stuff, otherwise, check
names, and use equivalent() then", then we don't need strictEquivalence() --
where's it used?
(If I represented the logic correctly above -- is that as simple as we can make
it? seems a touch complex)
I am not sure anything is 'broken' in practice here but I sense it could be
simpler.
> 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: 0.2
>
> Attachments: colt.jar, mahout-165-trove.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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