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https://issues.apache.org/jira/browse/MAHOUT-923?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13168465#comment-13168465
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jirapos...@reviews.apache.org commented on MAHOUT-923:
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bq. On 2011-12-13 13:08:20, Ted Dunning wrote:
bq. >
/trunk/core/src/main/java/org/apache/mahout/math/hadoop/DistributedRowMatrix.java,
line 199
bq. > <https://reviews.apache.org/r/3147/diff/5/?file=64279#file64279line199>
bq. >
bq. > I would really rather use standard terminology here.
bq. >
bq. > A mean row is a row that is that average of all others, but a row
mean would mean an average of the elements a single row. The plural form, row
means, indicates the means of all rows. What you are computing are the means
of every column.
bq. >
bq. > In contrast, R, Octave and Matlab all use columnMeans as the name of
the function being implemented here.
Sure. In Matlab/Octave I'm used to mean(A,1) (takes the mean across the 1st
dimension, ie. across rows, but done per column). I'll change this to
colMeans(), which seems to be clearer.
bq. On 2011-12-13 13:08:20, Ted Dunning wrote:
bq. >
/trunk/core/src/main/java/org/apache/mahout/math/hadoop/MatrixRowMeanJob.java,
lines 129-132
bq. > <https://reviews.apache.org/r/3147/diff/5/?file=64280#file64280line129>
bq. >
bq. > There are lots of lines with trailing white space. Isn't this
easily suppressed?
I can use sed, or perhaps there's a better way?
- Raphael
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On 2011-12-13 04:46:47, Raphael Cendrillon wrote:
bq.
bq. -----------------------------------------------------------
bq. This is an automatically generated e-mail. To reply, visit:
bq. https://reviews.apache.org/r/3147/
bq. -----------------------------------------------------------
bq.
bq. (Updated 2011-12-13 04:46:47)
bq.
bq.
bq. Review request for mahout, lancenorskog and Dmitriy Lyubimov.
bq.
bq.
bq. Summary
bq. -------
bq.
bq. Here's a patch with a simple job to calculate the row mean (column-wise
mean). One outstanding issue is the combiner, this requires a wrtiable class
IntVectorTupleWritable, where the Int stores the number of rows, and the Vector
stores the column-wise sum.
bq.
bq.
bq. This addresses bug MAHOUT-923.
bq. https://issues.apache.org/jira/browse/MAHOUT-923
bq.
bq.
bq. Diffs
bq. -----
bq.
bq.
/trunk/core/src/main/java/org/apache/mahout/math/hadoop/DistributedRowMatrix.java
1213474
bq.
/trunk/core/src/main/java/org/apache/mahout/math/hadoop/MatrixRowMeanJob.java
PRE-CREATION
bq.
/trunk/core/src/test/java/org/apache/mahout/math/hadoop/TestDistributedRowMatrix.java
1213474
bq.
bq. Diff: https://reviews.apache.org/r/3147/diff
bq.
bq.
bq. Testing
bq. -------
bq.
bq. Junit test
bq.
bq.
bq. Thanks,
bq.
bq. Raphael
bq.
bq.
> Row mean job for PCA
> --------------------
>
> Key: MAHOUT-923
> URL: https://issues.apache.org/jira/browse/MAHOUT-923
> Project: Mahout
> Issue Type: Improvement
> Components: Math
> Affects Versions: 0.6
> Reporter: Raphael Cendrillon
> Assignee: Raphael Cendrillon
> Fix For: Backlog
>
> Attachments: MAHOUT-923.patch, MAHOUT-923.patch
>
>
> Add map reduce job for calculating mean row (column-wise mean) of a
> Distributed Row Matrix for use in PCA.
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