You are viewing a plain text version of this content. The canonical link for it is here.

Posted to issues@commons.apache.org by "Gilles (JIRA)" <ji...@apache.org> on 2011/03/15 13:22:29 UTC

[jira] Commented: (MATH-546) Truncation issue in KMeansPlusPlusClusterer

    [ https://issues.apache.org/jira/browse/MATH-546?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13006890#comment-13006890 ] 

Gilles commented on MATH-546:
-----------------------------

Fixed in revision 1081744.
Thanks for the report and the patch.

Leaving open until an answer can be provided concerning the "EmptyClusterStrategy" question.


> Truncation issue in KMeansPlusPlusClusterer
> -------------------------------------------
>
>                 Key: MATH-546
>                 URL: https://issues.apache.org/jira/browse/MATH-546
>             Project: Commons Math
>          Issue Type: Bug
>    Affects Versions: 3.0
>            Reporter: Nate Paymer
>            Priority: Minor
>              Labels: cluster
>         Attachments: MATH-546.txt
>
>
> The for loop inside KMeansPlusPlusClusterer.chooseInitialClusters defines a variable
>   int sum = 0;
> This variable should have type double, rather than int.  Using an int causes the method to truncate the distances between points to (square roots of) integers.  It's especially bad when the distances between points are typically less than 1.
> As an aside, in version 2.2, this bug manifested itself by making the clusterer return empty clusters.  I wonder if the EmptyClusterStrategy would still be necessary if this bug were fixed.

--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira