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https://issues.apache.org/jira/browse/MAHOUT-1045?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13419914#comment-13419914
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Jeff Eastman commented on MAHOUT-1045:
--------------------------------------
I thought there was a problem there too (and I spent a bunch of time debugging
it) but consider: Their definition of inter-cluster density is the average
density of representative points within one standard deviation of a midpoint
half way between the closest representative points of each cluster. All of
those seem to be 0 in this dataset. It might be that sampling more
representative points would change that but I'm not sure at all.
I will be interested in what you find with some other cluster collections.
> Cluster evaluators returning bad results
> ----------------------------------------
>
> Key: MAHOUT-1045
> URL: https://issues.apache.org/jira/browse/MAHOUT-1045
> Project: Mahout
> Issue Type: Bug
> Components: Clustering
> Affects Versions: 0.6, 0.7, 0.8
> Environment: Several environments and data sets
> Reporter: Pat Ferrel
> Fix For: 0.8
>
> Attachments: MAHOUT-1045.patch, MAHOUT-1045.patch, MAHOUT-1045.patch,
> MAHOUT-1045.patch, first-time-density-nan.txt
>
>
> With real world crawl data the Intra-cluster density from ClusterEvaluator is
> almost always NaN. The CDbw inter-cluster density is almost always 0. I have
> also seen several cases where CDbw fails to return any results but have not
> tracked down why yet.
> I have sent a link to an 8G data set that reproduces these errors to Jeff
> Eastman.
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