edu.ucla.sspace.clustering.criterion

Class I2Function

java.lang.Object

edu.ucla.sspace.clustering.criterion.BaseFunction

edu.ucla.sspace.clustering.criterion.I2Function

All Implemented Interfaces:

CriterionFunction

public class I2Function
extends BaseFunction

This CriterionFunction measures the amount of internal similarity for each computed centroid. Centroids with higher internal similarity are given higher scores. It uses the magnitude of each centroid as the basis for this measurement.

Author:

Keith Stevens

Field Summary

Fields inherited from class edu.ucla.sspace.clustering.criterion.BaseFunction

assignments, centroids, clusterSizes, costs, matrix

Constructor Summary

Constructors

Constructor and Description
I2Function() Constructs a new I2Function.

Method Summary

Methods

Modifier and Type	Method and Description
protected double	getNewCentroidScore(int newCentroidIndex, DoubleVector dataPoint) Returns the new score for the cluster centroid indexed by newCentroidIndex when dataPoint is added to it.
protected double	getOldCentroidScore(DoubleVector vector, int oldCentroidIndex, int altClusterSize) Returns the new score for the cluster centroid represented by altCurrentCentroid with the new altClusterSize.
boolean	isMaximize() Returns true if this CriterionFunction tries to maximize it's score, and false otherwise.

Methods inherited from class edu.ucla.sspace.clustering.criterion.BaseFunction

assignments, centroids, clusterSizes, modifiedMagnitude, modifiedMagnitudeSqrd, score, setup, subSetup, subtract, subtractedMagnitude, subtractedMagnitudeSqrd, update, updateScores

Methods inherited from class java.lang.Object

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

Constructor Detail

I2Function

public I2Function()

Constructs a new I2Function.

Method Detail

getOldCentroidScore

protected double getOldCentroidScore(DoubleVector vector,
                         int oldCentroidIndex,
                         int altClusterSize)

Returns the new score for the cluster centroid represented by altCurrentCentroid with the new altClusterSize.

Specified by:

getOldCentroidScore in class BaseFunction

altClusterSize - The current updated cluster size

getNewCentroidScore

protected double getNewCentroidScore(int newCentroidIndex,
                         DoubleVector dataPoint)

Returns the new score for the cluster centroid indexed by newCentroidIndex when dataPoint is added to it. Implementations of this method should not actually add dataPoint to the centroid, but should instead use the helper functions provided to compute the new score.

Specified by:

getNewCentroidScore in class BaseFunction

Parameters:

newCentroidIndex - The index of the current alternate centroid

dataPoint - The current data point that is being reassigned

isMaximize

public boolean isMaximize()

Returns true if this CriterionFunction tries to maximize it's score, and false otherwise.