weka.clusterers
Class DensityBasedClusterer

java.lang.Object
  weka.clusterers.Clusterer
      weka.clusterers.DensityBasedClusterer

All Implemented Interfaces:

java.lang.Cloneable, java.io.Serializable

Direct Known Subclasses:

EM, MakeDensityBasedClusterer

public abstract class DensityBasedClusterer

extends Clusterer

Abstract clustering model that produces (for each test instance) an estimate of the membership in each cluster (ie. a probability distribution).

Version:

$Revision: 1.1 $

Author:

Mark Hall (mhall@cs.waikato.ac.nz), Eibe Frank (eibe@cs.waikato.ac.nz)

See Also:

Serialized Form

Constructor Summary

DensityBasedClusterer()

Method Summary

abstract double[]	clusterPriors() Returns the prior probability of each cluster.
double[]	distributionForInstance(Instance instance) Returns the cluster probability distribution for an instance.
double	logDensityForInstance(Instance instance) Computes the density for a given instance.
abstract double[]	logDensityPerClusterForInstance(Instance instance) Computes the log of the conditional density (per cluster) for a given instance.
protected double[]	logJointDensitiesForInstance(Instance inst) Returns the logs of the joint densities for a given instance.

Methods inherited from class weka.clusterers.Clusterer

buildClusterer, clusterInstance, forName, makeCopies, numberOfClusters

Methods inherited from class java.lang.Object

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

Constructor Detail

DensityBasedClusterer

public DensityBasedClusterer()

Method Detail

clusterPriors

public abstract double[] clusterPriors()
                                throws java.lang.Exception

Returns the prior probability of each cluster.

Returns:

the prior probability for each cluster

Throws:

java.lang.Exception - if priors could not be returned successfully

logDensityPerClusterForInstance

public abstract double[] logDensityPerClusterForInstance(Instance instance)
                                                  throws java.lang.Exception

Computes the log of the conditional density (per cluster) for a given instance.

Parameters:

instance - the instance to compute the density for

Returns:

the density.

Throws:

java.lang.Exception - if the density could not be computed successfully

logDensityForInstance

public double logDensityForInstance(Instance instance)
                             throws java.lang.Exception

Computes the density for a given instance.

Parameters:

instance - the instance to compute the density for

Returns:

the density.

Throws:

java.lang.Exception - if the density could not be computed successfully

distributionForInstance

public double[] distributionForInstance(Instance instance)
                                 throws java.lang.Exception

Returns the cluster probability distribution for an instance. Will simply have a probability of 1 for the chosen cluster and 0 for the others.

Overrides:

distributionForInstance in class Clusterer

Parameters:

instance - the instance to be clustered

Returns:

the probability distribution

Throws:

java.lang.Exception - if distribution could not be computed successfully

logJointDensitiesForInstance

protected double[] logJointDensitiesForInstance(Instance inst)
                                         throws java.lang.Exception

Returns the logs of the joint densities for a given instance.

Parameters:

inst - the instance

Returns:

the array of values

Throws:

java.lang.Exception - if values could not be computed