de.lmu.ifi.dbs.elki.algorithm.clustering.hierarchical.linkage

Class FlexibleBetaLinkage

java.lang.Object

de.lmu.ifi.dbs.elki.algorithm.clustering.hierarchical.linkage.FlexibleBetaLinkage

All Implemented Interfaces:

Linkage

@Reference(authors="G. N. Lance, W. T. Williams",
           title="A general theory of classificatory sorting strategies 1. Hierarchical systems",
           booktitle="The Computer Journal 9.4",
           url="https://doi.org/10.1093/comjnl/9.4.373",
           bibkey="doi:10.1093/comjnl/9.4.373")
 @Alias(value={"flex","beta","de.lmu.ifi.dbs.elki.algorithm.clustering.hierarchical.FlexibleBetaLinkageMethod"})
 @Priority(value=-2)
public class FlexibleBetaLinkage
extends java.lang.Object
implements Linkage

Flexible-beta linkage as proposed by Lance and Williams.

Beta values larger than 0 cause chaining, and are thus not recommended. Instead, choose a value between -1 and 0.

The general form of the recursive definition is: \[d_{\text{Flexible},\beta}(A\cup B, C) := \tfrac{1-\beta}{2} d(A,C) + \tfrac{1-\beta}{2} d(B,C) + \beta d(A,B) \]

Reference:

G. N. Lance, W. T. Williams
A general theory of classificatory sorting strategies
1. Hierarchical systems
The Computer Journal 9.4

Since:

0.7.5

Author:

Erich Schubert

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	FlexibleBetaLinkage.Parameterizer Parameterization class.

Field Summary

Fields

Modifier and Type	Field and Description
(package private) double	alpha Alpha parameter, derived from beta.
(package private) double	beta Beta parameter

Constructor Summary

Constructors

Constructor and Description
FlexibleBetaLinkage(double beta) Constructor.

Method Summary

Modifier and Type	Method and Description
double	combine(int sizex, double dx, int sizey, double dy, int sizej, double dxy) Compute combined linkage for two clusters.

Methods inherited from class java.lang.Object

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

Methods inherited from interface de.lmu.ifi.dbs.elki.algorithm.clustering.hierarchical.linkage.Linkage

initial, restore

Field Detail

alpha

double alpha

Alpha parameter, derived from beta.

beta

double beta

Beta parameter

Constructor Detail

FlexibleBetaLinkage

public FlexibleBetaLinkage(double beta)

Constructor.

Parameters:

beta - Beta parameter

Method Detail

combine

public double combine(int sizex,
                      double dx,
                      int sizey,
                      double dy,
                      int sizej,
                      double dxy)

Description copied from interface: Linkage

Compute combined linkage for two clusters.

Specified by:

combine in interface Linkage

Parameters:

sizex - Size of first cluster x before merging

dx - Distance of cluster x to j before merging

sizey - Size of second cluster y before merging

dy - Distance of cluster y to j before merging

sizej - Size of candidate cluster j

dxy - Distance between clusters x and y before merging

Returns:

Combined distance