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https://issues.apache.org/jira/browse/MAHOUT-843?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13150323#comment-13150323
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Paritosh Ranjan commented on MAHOUT-843:
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Jeff, I was analyzing the idea of the MapReduce version of the PostProcessor. I
have a query on the solution you have proposed.
As you said "Each reducer will receive all the VW points for a single cluster
and will output a part file with key=clusterId value= {VW points}".
What will happen if the number of reducers available is less than the number of
clusters? Then, I think, each reducer will get more than once cluster's
vectors. Please correct me if I am wrong.
> Top Down Clustering
> -------------------
>
> Key: MAHOUT-843
> URL: https://issues.apache.org/jira/browse/MAHOUT-843
> Project: Mahout
> Issue Type: New Feature
> Components: Clustering
> Affects Versions: 0.6
> Reporter: Paritosh Ranjan
> Labels: clustering, patch
> Fix For: 0.6
>
> Attachments: MAHOUT-843-patch, MAHOUT-843-patch-only-postprocessor,
> MAHOUT-843-patch-only-postprocessor-v1,
> MAHOUT-843-patch-only-postprocessor-v2, MAHOUT-843-patch-v1,
> Top-Down-Clustering-patch
>
>
> Top Down Clustering works in multiple steps. The first step is to find
> comparative bigger clusters. The second step is to cluster the bigger chunks
> into meaningful clusters. This can performance while clustering big amount of
> data. And, it also removes the dependency of providing input clusters/numbers
> to the clustering algorithm.
> The "big" is a relative term, as well as the smaller "meaningful" terms. So,
> the control of this "bigger" and "smaller/meaningful" clusters will be
> controlled by the user.
> Which clustering algorithm to be used in the top level and which to use in
> the bottom level can also be selected by the user. Initially, it can be done
> for only one/few clustering algorithms, and later, option can be provided to
> use all the algorithms ( which suits the case ).
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