Class WPGMALinkage

java.lang.Object
smile.clustering.linkage.Linkage
smile.clustering.linkage.WPGMALinkage

public class WPGMALinkage extends Linkage
Weighted Pair Group Method with Arithmetic mean. WPGMA down-weights the largest group by giving equal weights to the two branches of the dendrogram that are about to fuse.

Note that the terms weighted and unweighted refer to the final result, not the math by which it is achieved. Thus, the simple averaging in WPGMA produces a weighted result, and the proportional averaging in UPGMA produces an unweighted result.

  • Constructor Details

    • WPGMALinkage

      public WPGMALinkage(double[][] proximity)
      Constructor.
      Parameters:
      proximity - the proximity matrix. Only the lower half will be referred.
    • WPGMALinkage

      public WPGMALinkage(int size, float[] proximity)
      Constructor. Initialize the linkage with the lower triangular proximity matrix.
      Parameters:
      size - the data size.
      proximity - the column-wise linearized proximity matrix that stores only the lower half. The length of proximity should be size * (size+1) / 2. To save space, Linkage will use this argument directly without copy. The elements may be modified.
  • Method Details

    • of

      public static WPGMALinkage of(double[][] data)
      Computes the proximity and the linkage.
      Parameters:
      data - the data points.
      Returns:
      the linkage.
    • of

      public static <T> WPGMALinkage of(T[] data, Distance<T> distance)
      Computes the proximity and the linkage.
      Type Parameters:
      T - the data type of points.
      Parameters:
      data - the data points.
      distance - the distance function.
      Returns:
      the linkage.
    • toString

      public String toString()
      Overrides:
      toString in class Object
    • merge

      public void merge(int i, int j)
      Description copied from class: Linkage
      Merges two clusters into one and update the proximity matrix.
      Specified by:
      merge in class Linkage
      Parameters:
      i - cluster id.
      j - cluster id.