org.apache.commons.math3.ml.clustering

## Class MultiKMeansPlusPlusClusterer<T extends Clusterable>

- java.lang.Object
- - org.apache.commons.math3.ml.clustering.Clusterer<T>
  - - org.apache.commons.math3.ml.clustering.MultiKMeansPlusPlusClusterer<T>

- Type Parameters:
    `T` - type of the points to cluster

      public class MultiKMeansPlusPlusClusterer<T extends Clusterable>
      extends Clusterer<T>

  A wrapper around a k-means++ clustering algorithm which performs multiple trials and returns the best solution.
  Since:
    3.2

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `MultiKMeansPlusPlusClusterer(KMeansPlusPlusClusterer<T> clusterer, int numTrials)` Build a clusterer.
    `MultiKMeansPlusPlusClusterer(KMeansPlusPlusClusterer<T> clusterer, int numTrials, ClusterEvaluator<T> evaluator)` Build a clusterer.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `List<CentroidCluster<T>>` | `cluster(Collection<T> points)` Runs the K-means++ clustering algorithm.
    `KMeansPlusPlusClusterer<T>` | `getClusterer()` Returns the embedded k-means clusterer used by this instance.
    `ClusterEvaluator<T>` | `getClusterEvaluator()` Returns the `ClusterEvaluator` used to determine the "best" clustering.
    `int` | `getNumTrials()` Returns the number of trials this instance will do.

    - ### Methods inherited from class org.apache.commons.math3.ml.clustering.Clusterer

      `distance, getDistanceMeasure`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### MultiKMeansPlusPlusClusterer

          public MultiKMeansPlusPlusClusterer(KMeansPlusPlusClusterer<T> clusterer,
                                      int numTrials)

      Build a clusterer.
      Parameters:
        `clusterer` - the k-means clusterer to use
        `numTrials` - number of trial runs

    - #### MultiKMeansPlusPlusClusterer

          public MultiKMeansPlusPlusClusterer(KMeansPlusPlusClusterer<T> clusterer,
                                      int numTrials,
                                      ClusterEvaluator<T> evaluator)

      Build a clusterer.
      Parameters:
        `clusterer` - the k-means clusterer to use
        `numTrials` - number of trial runs
        `evaluator` - the cluster evaluator to use
      Since:
        3.3

  - ### Method Detail

    - #### getClusterer

          public KMeansPlusPlusClusterer<T> getClusterer()

      Returns the embedded k-means clusterer used by this instance.
      Returns:
        the embedded clusterer

    - #### getNumTrials

          public int getNumTrials()

      Returns the number of trials this instance will do.
      Returns:
        the number of trials

    - #### getClusterEvaluator

          public ClusterEvaluator<T> getClusterEvaluator()

      Returns the `ClusterEvaluator` used to determine the "best" clustering.
      Returns:
        the used `ClusterEvaluator`
      Since:
        3.3

    - #### cluster

          public List<CentroidCluster<T>> cluster(Collection<T> points)
                                                               throws MathIllegalArgumentException,
                                                                      ConvergenceException

      Runs the K-means++ clustering algorithm.
      Specified by:
        `cluster` in class `Clusterer<T extends Clusterable>`
      Parameters:
        `points` - the points to cluster
      Returns:
        a list of clusters containing the points
      Throws:
        `MathIllegalArgumentException` - if the data points are null or the number of clusters is larger than the number of data points
        `ConvergenceException` - if an empty cluster is encountered and the underlying `KMeansPlusPlusClusterer` has its `KMeansPlusPlusClusterer.EmptyClusterStrategy` is set to `ERROR`.

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