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https://issues.apache.org/jira/browse/MAHOUT-626?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jeff Eastman updated MAHOUT-626:
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Fix Version/s: (was: 0.5)
> T1 and T2 Values in Canopy (& MeanShift)
> -----------------------------------------
>
> Key: MAHOUT-626
> URL: https://issues.apache.org/jira/browse/MAHOUT-626
> Project: Mahout
> Issue Type: Improvement
> Components: Clustering
> Affects Versions: 0.5
> Reporter: Jeff Eastman
> Assignee: Jeff Eastman
> Attachments: CanopyT3T4.patch
>
>
> Users are reporting that the T1 and T2 threshold values which work in
> sequential mode don't work as well in the mapreduce mode because both the
> mapper and reducer are using the same values. The effect of coalescing a
> number of points into a single centroid done by the mapper changes the
> distances enough that independent threshold values are needed in the reducer.
> Here is a patch which implements optional T3 and T4 threshold values which
> are only used by the canopy reducer. Convenience methods have been added for
> API compatibility and defaults included so that these values will default to
> T1 and T2. A new unit test confirms the thresholds are being set correctly.
> If this works out as a positive improvement, I will make the same changes to
> MeanShift and commit them
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