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https://issues.apache.org/jira/browse/MAHOUT-904?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13174873#comment-13174873
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jirapos...@reviews.apache.org commented on MAHOUT-904:
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This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/3092/
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(Updated 2011-12-22 16:03:47.932528)


Review request for mahout, Ted Dunning, lancenorskog, and Grant Ingersoll.


Changes
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Grant's changes


Summary
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Early support for randomizing input in SplitInput class. This is an early start 
but I've posted it up just to check if I'm on the right track.  A couple of 
comments:

  - currently the code runs through the entire file looking for the line 
corresponding to the random index. This has to be repeated for every line, 
which is slow and somewhat ugly.
  - the permutation indices are stored in an array. This could lead to scaling 
issues if the number of input lines is large. This problem may also exist with 
ridx in the existing code. One option is to use a linear feedback shift 
register to generate a permutation sequence on the fly.

Any suggestions would be very welcome!


This addresses bug MAHOUT-904.
    https://issues.apache.org/jira/browse/MAHOUT-904


Diffs (updated)
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  /trunk/core/src/main/java/org/apache/mahout/common/AbstractJob.java 1222286 
  /trunk/integration/src/main/java/org/apache/mahout/utils/SplitInput.java 
1222286 
  /trunk/integration/src/main/java/org/apache/mahout/utils/SplitInputJob.java 
PRE-CREATION 
  /trunk/integration/src/test/java/org/apache/mahout/utils/SplitInputTest.java 
1222286 

Diff: https://reviews.apache.org/r/3092/diff


Testing
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Thanks,

Raphael


                
> SplitInput should support randomizing the input
> -----------------------------------------------
>
>                 Key: MAHOUT-904
>                 URL: https://issues.apache.org/jira/browse/MAHOUT-904
>             Project: Mahout
>          Issue Type: Improvement
>            Reporter: Grant Ingersoll
>            Assignee: Raphael Cendrillon
>              Labels: MAHOUT_INTRO_CONTRIBUTE
>         Attachments: MAHOUT-904.patch, MAHOUT-904.patch, MAHOUT-904.patch, 
> MAHOUT-904.patch, MAHOUT-904.patch
>
>
> For some learning tasks, we need the input to be randomized (SGD) instead of 
> blocks of labels all at once.  SplitInput is a useful tool for setting up 
> train/test files but it currently doesn't support randomizing the input.

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