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https://issues.apache.org/jira/browse/MAHOUT-1130?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13537080#comment-13537080
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Andrey Davydov commented on MAHOUT-1130:
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I found this bug while I worked with 6500 vectors sample and I want to generate 
30 initial clusters. I made more then 50 experiments. Every time all results 
was with id more then 5000.

I can investigate more, but only on new year vacations (in Russia we have free 
week in the beginig of year). Also I can implement unit test and make some 
calculus to find way to achive best distribution of clusters.
                
> Wrong logic in org.apache.mahout.clustering.kmeans.RandomSeedGenerator
> ----------------------------------------------------------------------
>
>                 Key: MAHOUT-1130
>                 URL: https://issues.apache.org/jira/browse/MAHOUT-1130
>             Project: Mahout
>          Issue Type: Bug
>         Environment: mahout 0.7 from maven central
>            Reporter: Andrey Davydov
>
> There is following code in line 101:
>               } else if (random.nextInt(currentSize + 1) != 0) { // with 
> chance 1/(currentSize+1) pick new element
> but it actually means pick new element with chance currentSize/(currentSize+1)
> so generator takes initial centers from the end of source data file.
> It seems that chance of replace vector in output set should decrease with 
> number of processed input vectors

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