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From "Hudson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HAMA-834) Fix KMeans example
Date Mon, 06 Jan 2014 14:23:52 GMT

    [ https://issues.apache.org/jira/browse/HAMA-834?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13863008#comment-13863008
] 

Hudson commented on HAMA-834:
-----------------------------

SUCCESS: Integrated in Hama-trunk #225 (See [https://builds.apache.org/job/Hama-trunk/225/])
HAMA-834: Fix KMeans example (millecker: rev 1555747)
* /hama/trunk/CHANGES.txt
* /hama/trunk/core/src/main/java/org/apache/hama/pipes/util/SequenceFileDumper.java
* /hama/trunk/examples/src/main/java/org/apache/hama/examples/Kmeans.java
* /hama/trunk/ml/src/main/java/org/apache/hama/ml/kmeans/KMeansBSP.java
* /hama/trunk/ml/src/test/java/org/apache/hama/ml/kmeans/TestKMeansBSP.java


> Fix KMeans example
> ------------------
>
>                 Key: HAMA-834
>                 URL: https://issues.apache.org/jira/browse/HAMA-834
>             Project: Hama
>          Issue Type: Bug
>          Components: examples, machine learning
>    Affects Versions: 0.6.3
>            Reporter: Martin Illecker
>            Assignee: Martin Illecker
>              Labels: example
>             Fix For: 0.7.0
>
>         Attachments: HAMA-834.patch, HAMA-834_v02.patch, HAMA-834_v03.patch
>
>
> Fix problems in KMeans example and revise test case.
> 1) Typo \[1] and input path issue
> 2) Wrong *summationCount* in assignCentersInternal
> *summationCount* should also be incremented if \[2] 
> {code}
> if (clusterCenter == null) {
>   newCenterArray[lowestDistantCenter] = key;
> }
> {code}
> Otherwise *summationCount* may stay zero when only one value is assigned. Then this zero
will be propagated to *incrementSum* \[3] and might cause a divide by zero in \[4]. 
> By the way if we add three vectors and the *summationCount* would only be two, this will
lead to wrong results. Because later we are dividing the vector by the amount of increments.
> 3) Results depend on the amount *numBspTask*
> (results vary if *numBspTask* is changed)
> \[1]
> https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/kmeans/KMeansBSP.java#L518-519
> \[2] https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/kmeans/KMeansBSP.java#L249
> \[3]
> https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/kmeans/KMeansBSP.java#L161
> \[4] https://github.com/apache/hama/blob/trunk/ml/src/main/java/org/apache/hama/ml/kmeans/KMeansBSP.java#L172



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