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Posted to dev@mahout.apache.org by "Dan Filimon (JIRA)" <ji...@apache.org> on 2013/04/10 23:17:15 UTC

[jira] [Created] (MAHOUT-1190) SequentialAccessSparseVector function assignment is very slow

Dan Filimon created MAHOUT-1190:
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             Summary: SequentialAccessSparseVector function assignment is very slow
                 Key: MAHOUT-1190
                 URL: https://issues.apache.org/jira/browse/MAHOUT-1190
             Project: Mahout
          Issue Type: Bug
            Reporter: Dan Filimon


Currently when calling .assign() on a SASV with another vector and a custom function, it will iterate through it and assign every single entry while also referring it by index.

This makes the process *hugely* expensive. (on a run of BallKMeans on the 20 newsgroups data set, profiling reveals that 92% of the runtime was spent updating assigning the vectors).

Here's a prototype patch:
https://github.com/dfilimon/mahout/commit/63998d82bb750150a6ae09052dadf6c326c62d3d

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