[jira] [Created] (MATH-1521) A interface to implements various of clusters external measurers

["Chen Tao (Jira)" <ji...@apache.org>]

Chen Tao created MATH-1521:
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             Summary: A interface to implements various of clusters external measurers
                 Key: MATH-1521
                 URL: https://issues.apache.org/jira/browse/MATH-1521
             Project: Commons Math
          Issue Type: New Feature
            Reporter: Chen Tao


There are many clusters evaluation algorithm:
[scikit-learn clustering-performance-evaluation|https://scikit-learn.org/stable/modules/clustering.html#clustering-performance-evaluation]

They can be divided into 2 categories: “External Measurers” and "Internal Measurers".

The “External Measurers” evaluator clusters reference to another clusters.

As opposed to “Internal Measurers”, the "External Measurers" may be:

{code:java}
public interface ClusterExternalEvaluator {
    /**
     * @param cList List of clusters.
     * @return the score attributed by the evaluator.
     */
    <T extends Clusterable> double score(List<? extends Cluster<? extends T>> clusters1, List<? extends Cluster<? extends T>> clusters2);
    /**
     * @param a Score computed by this evaluator.
     * @param b Score computed by this evaluator.
     * @return true if the evaluator considers score {@code a} is
     * considered better than score {@code b}.
     */
    boolean isBetterScore(double a, double b);
{code}




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