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From "Dmitriy Lyubimov (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (MAHOUT-1103) clusterpp is not writing directories for all clusters
Date Mon, 22 Oct 2012 18:00:13 GMT

    [ https://issues.apache.org/jira/browse/MAHOUT-1103?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13481557#comment-13481557
] 

Dmitriy Lyubimov edited comment on MAHOUT-1103 at 10/22/12 6:00 PM:
--------------------------------------------------------------------

bq. Hi Dmitriy, sorry for going a little off topic here, but could you elaborate on this?
I've been experimenting with using either cosine or tanimoto distance on the USigma output
of ssvd with -pca true. Are those not appropriate distance measures for the -pca output?

I'll reply on user list, that way somebody will surely try to correct me since i have been
doing straightforward LSA only.
                
      was (Author: dlyubimov):
    bq. Since its not working for even two clusters, I don't see any problem due to the Partitioner.
The input here looks like the output of SSVD. There has been problems reported earlier also,
where SSVD output was creating problems in clustering.

I'll reply on user list, that way somebody will surely try to correct me since i have been
doing straightforward LSA only.
                  
> clusterpp is not writing directories for all clusters
> -----------------------------------------------------
>
>                 Key: MAHOUT-1103
>                 URL: https://issues.apache.org/jira/browse/MAHOUT-1103
>             Project: Mahout
>          Issue Type: Bug
>          Components: Clustering
>    Affects Versions: 0.8
>            Reporter: Matt Molek
>            Assignee: Paritosh Ranjan
>              Labels: clusterpp
>
> After running kmeans clustering on a set of ~3M points, clusterpp fails to populate directories
for some clusters, no matter what k is.
> I've tested this on my data with k = 300, 250, 150, 100, 50, 25, 10, 5, 2
> Even with k=2 only one cluster directory was created. For each reducer that fails to
produce directories there is an empty part-r-* file in the output directory.
> Here is my command sequence for the k=2 run:
> {noformat}bin/mahout kmeans -i ssvd2/USigma -c 2clusters/init-clusters -o 2clusters/pca-clusters
-dm org.apache.mahout.common.distance.TanimotoDistanceMeasure -cd 0.05 -k 2 -x 15 -cl
> bin/mahout clusterdump -i 2clusters/pca-clusters/clusters-*-final -o 2clusters.txt
> bin/mahout clusterpp -i 2clusters/pca-clusters -o 2clusters/bottom{noformat} 
> The output of clusterdump shows two clusters: VL-3742464 and VL-3742466 containing 2585843
and 1156624 points respectively.
> Discussion on the user mailing list suggested that this might be caused by the default
hadoop hash partitioner. The hashes of these two clusters aren't identical, but they are close.
Putting both cluster names into a Text and caling hashCode() gives:
> VL-3742464 -> -685560454
> VL-3742466 -> -685560452
> Finally, when running with "-xm sequential", everything performs as expected.

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