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https://issues.apache.org/jira/browse/MAHOUT-900?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13158839#comment-13158839
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Hudson commented on MAHOUT-900:
-------------------------------
Integrated in Mahout-Quality #1208 (See
[https://builds.apache.org/job/Mahout-Quality/1208/])
MAHOUT-900 fix sampling logic and handle case of < k elements
srowen : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1207508
Files :
*
/mahout/trunk/core/src/main/java/org/apache/mahout/clustering/kmeans/RandomSeedGenerator.java
> RandomSeedGenerator samples / output k texts incorrectly
> --------------------------------------------------------
>
> Key: MAHOUT-900
> URL: https://issues.apache.org/jira/browse/MAHOUT-900
> Project: Mahout
> Issue Type: Bug
> Components: Clustering
> Affects Versions: 0.5
> Reporter: Sean Owen
> Assignee: Sean Owen
> Priority: Minor
> Fix For: 0.6
>
> Attachments: MAHOUT-900.patch
>
>
> {code}
> int currentSize = chosenTexts.size();
> if (currentSize < k) {
> chosenTexts.add(newText);
> chosenClusters.add(newCluster);
> } else if (random.nextInt(currentSize + 1) == 0) { // with chance
> 1/(currentSize+1) pick new element
> int indexToRemove = random.nextInt(currentSize); // evict one
> chosen randomly
> chosenTexts.remove(indexToRemove);
> chosenClusters.remove(indexToRemove);
> chosenTexts.add(newText);
> chosenClusters.add(newCluster);
> }
> {code}
> The second "if" condition ought to be "!= 0", right? Only if it is 0 do we
> skip the body, which removes an existing element, since the new element
> itself is evicted.
> Second, this code:
> {code}
> for (int i = 0; i < k; i++) {
> writer.append(chosenTexts.get(i), chosenClusters.get(i));
> }
> {code}
> ... assumes that at least k elements existed in the input, and fails
> otherwise. Probably need to cap this.
> Patch attached.
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