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https://issues.apache.org/jira/browse/MAHOUT-1020?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jeff Eastman reassigned MAHOUT-1020:
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Assignee: Jeff Eastman
> The Cluster Evaluator is returning bad results
> ----------------------------------------------
>
> Key: MAHOUT-1020
> URL: https://issues.apache.org/jira/browse/MAHOUT-1020
> Project: Mahout
> Issue Type: Bug
> Components: Clustering
> Affects Versions: 0.6
> Environment: Various environments and data sets. Mahout 0.6, 0.7
> trunk not tested.
> Reporter: Pat Ferrel
> Assignee: Jeff Eastman
> Fix For: 0.7
>
>
> Conversation with between Pat Ferrel and Jeff Eastman on the user list
> Hi Pat,
> I don't have a good answer here. Evidently, something in CDbw has become
> broken and you are the first to notice. When I run TestCDbwEvaluator, the
> values for k-means and fuzzy-k are clearly incorrect. The values for Canopy,
> MeanShift and Dirichlet are not so obviously incorrect but I remain
> suspicious. Something must have become broken in the recent clustering
> refactoring.
> From the method CDbwEvaluator.invalidCluster comment (used to enable pruning):
> * Return if the cluster is valid. Valid clusters must have more than 2
> representative points,
> * and at least one of them must be different than the cluster center. This
> is because the
> * representative points extraction will duplicate the cluster center if it
> is empty.
> Oddly enough, inspection of the test log indicates that only k-means and
> fuzzy-k are not pruning clusters. Clearly some more investigation is needed.
> I will take a look at it tomorrow. In the mean time if you develop any
> additional insight please do share it with us.
> Thanks,
> Jeff
> On 5/17/12 3:53 PM, Pat Ferrel wrote:
> > I built a tool that iterates through a list of values for k on the same
> > data and spits out the CDbw and ClusterEvaluator results each time.
> >
> > When the evaluator or CDbw prunes a cluster, how do I interpret that? They
> > seem to throw out the same clusters on a given run. Also CDbw always
> > returns an inter-cluster density of 0?
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