[jira] [Updated] (MAHOUT-1086) Mean Shift Test Now Produces 4 Clusters

["Ted Dunning (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/MAHOUT-1086?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ted Dunning updated MAHOUT-1086:
--------------------------------

    Attachment: 0001-MAHOUT-1086-Deal-with-round-off-errors-in-computing-.patch

Here is a patch in git format.  I can't remember if jenkins will apply that cleanly or not.

The problem was round-off errors that happened differently when the ordering of operations is different.  That ordering is changed when caching is changed and this problem comes up.

The expected result of this patch is that the old error will come back (reversed).  That is, you should see
{code}
Failed tests:   testCanopyEuclideanMRJobNoClustering(org.apache.mahout.clustering.meanshift.TestMeanShift): count expected:<4> but was:<3>
{code}

                
> Mean Shift Test Now Produces 4 Clusters
> ---------------------------------------
>
>                 Key: MAHOUT-1086
>                 URL: https://issues.apache.org/jira/browse/MAHOUT-1086
>             Project: Mahout
>          Issue Type: Bug
>          Components: Clustering
>    Affects Versions: 0.7
>            Reporter: Jeff Eastman
>         Attachments: 0001-MAHOUT-1086-Deal-with-round-off-errors-in-computing-.patch
>
>
> Something changed in Mahout around 9/6/12 that caused TestMeanShift.testCanopyEuclideanMRJobNoClustering to return 4 clusters rather than 3. All of the other tests using the same data still return 3 clusters. No changes were made to any of the MeanShiftCanopy classes other than 1 formatting change to the driver so I'm at a loss to the cause.

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