Thorsten Schäfer created MATH-1315:
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Summary: MultiKMeansPlusPlusClusterer buggy for alternative
evaluators
Key: MATH-1315
URL: https://issues.apache.org/jira/browse/MATH-1315
Project: Commons Math
Issue Type: Bug
Affects Versions: 3.5
Reporter: Thorsten Schäfer
I just looked into the source code for the MultiKMeansPlusPlusClusterer and
realized that it would return null in case of an alternative evaluator that
favors bigger values instead of smaller ones:
The basic idea of the clustering method is that we perform n clusterings and
choose the best result. The decision what's the best result is performed by the
evaluator, which by default assumes smaller values are better.
According to the documentation, we can also provide a different evaluator,
which for instance would decide that bigger values are better, but given we
initialize the best value with Double.POSITIVE_INFINITY in method
MultiKMeansPlusPlusClusterer.cluster(Collection<T>), we would never find a
"better" result and thus always return null.
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