[
https://issues.apache.org/jira/browse/MAHOUT-165?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12779496#action_12779496
]
Sean Owen commented on MAHOUT-165:
----------------------------------
I think this deserves a bit more thought. I was actually surprised to hear
iterateNonZero() doesn't iterate in order?? that is surprising. Can that be
right? The argument I suppose is that some callers don't need ordering so why
provide it, for efficiency reasons. If that's the thinking, then hashCode()
needs to simply take account of the index, not order the elements. A
consistent/correct hash code doesn't necessarily need this.
> 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.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
