[jira] [Updated] (MAHOUT-1130) Wrong logic in org.apache.mahout.clustering.kmeans.RandomSeedGenerator

["Sebastian Schelter (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/MAHOUT-1130?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Sebastian Schelter updated MAHOUT-1130:
---------------------------------------

    Attachment: MAHOUT-1130.patch

Patch that makes the RandomSeedGenerator use reservoir sampling to pick a uniform sample of seed vectors. Can someone have a look at it?
                
> 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
>         Attachments: MAHOUT-1130.patch
>
>
> 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

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira