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Posted to dev@mahout.apache.org by "ASF GitHub Bot (JIRA)" <ji...@apache.org> on 2014/06/13 16:24:01 UTC
[jira] [Commented] (MAHOUT-1580) Optimize getNumNonZeroElements
[ https://issues.apache.org/jira/browse/MAHOUT-1580?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14030667#comment-14030667 ]
ASF GitHub Bot commented on MAHOUT-1580:
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GitHub user sscdotopen opened a pull request:
https://github.com/apache/mahout/pull/17
MAHOUT-1580 Optimize getNumNonZeroElements()
Can someone have a look at the changes? The basic idea is to directly work on the internal datastructures instead of going through the non-zeroes iterator.
A quick benchmark should 7x performance on dense and 3x performance on sequential access sparse vectors.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/sscdotopen/mahout MAHOUT-1580
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/mahout/pull/17.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #17
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commit 25b99847f43e4cb29b71064921d52c373c221442
Author: ssc <ss...@apache.org>
Date: 2014-06-13T12:32:24Z
custom implementations for main vectors
commit 50fc20826893d2af3a7fafe94c4ac6ae6198e622
Author: ssc <ss...@apache.org>
Date: 2014-06-13T12:44:49Z
added optimization for permuted view
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> Optimize getNumNonZeroElements
> ------------------------------
>
> Key: MAHOUT-1580
> URL: https://issues.apache.org/jira/browse/MAHOUT-1580
> Project: Mahout
> Issue Type: Improvement
> Components: Math
> Reporter: Sebastian Schelter
> Assignee: Sebastian Schelter
> Fix For: 1.0
>
>
> getNumNonZeroElements in AbstractVector uses the nonZeroes -iterator internally which adds a lot of overhead for certain types of vectors, e.g. the dense ones. We should add custom implementations here.
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