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https://issues.apache.org/jira/browse/MAHOUT-463?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12897662#action_12897662
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Hui Wen Han commented on MAHOUT-463:
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/**
* distributed implementation of cosine similarity that does not center its data
*/
public class DistributedUncenteredCosineVectorSimilarity extends
AbstractDistributedVectorSimilarity {
@Override
protected double doComputeResult(int rowA, int rowB, Iterable<Cooccurrence>
cooccurrences, double weightOfVectorA,
double weightOfVectorB, int numberOfColumns) {
int n = 0;
double sumXY = 0.0;
double sumX2 = 0.0;
double sumY2 = 0.0;
for (Cooccurrence cooccurrence : cooccurrences) {
double x = cooccurrence.getValueA();
double y = cooccurrence.getValueB();
sumXY += x * y;
sumX2 += x * x;
sumY2 += y * y;
n++;
}
if (n == 0) {
return Double.NaN;
}
double denominator = Math.sqrt(sumX2) * Math.sqrt(sumY2);
if (denominator == 0.0) {
// One or both vectors has -all- the same values;
// can't really say much similarity under this measure
return Double.NaN;
}
return sumXY / denominator;
}
}
this one will always return 1.0
> Boolean Data can not get any recommendation by running RecommnenderJob
> ----------------------------------------------------------------------
>
> Key: MAHOUT-463
> URL: https://issues.apache.org/jira/browse/MAHOUT-463
> Project: Mahout
> Issue Type: Test
> Components: Collaborative Filtering
> Affects Versions: 0.4
> Reporter: Hui Wen Han
> Fix For: 0.4
>
> Attachments: MAHOUT-463-2.patch, MAHOUT-463.patch
>
>
> Boolean Preference Data can not get any recommendation by run RecommnenderJob,
> but It can get data using the build in about Aprl.
> It seems that it can not get any data by running RowSimilarityJob
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