edu.indiana.iucbrf.feature.stats
Class InformationTheory

java.lang.Object
  edu.indiana.iucbrf.feature.stats.InformationTheory

public class InformationTheory
extends java.lang.Object

Field Summary

protected java.util.HashSet	allKeys
protected java.util.ArrayList	cases
protected Domain	domain
protected double	entropyC
protected java.util.HashSet	keysOfInterest
protected java.util.HashMap	keyToGain
protected java.util.HashMap	keyToGainRatio
protected FeatureKey	maxGainKey
protected FeatureKey	maxGainRatioKey
protected KeyToValueToDouble	probKeyToCountMap
protected FeatureKey	solutionFeatureKey
protected FeatureSpec	solutionFeatureSpec
protected java.util.HashMap	solValueToCount

Constructor Summary

InformationTheory(Domain domain)
Creates a new instance of InformationTheory.

InformationTheory(Domain domain, java.util.HashSet allKeys)
Creates a new instance of InformationTheory

Method Summary

double	calcEntropy(int numCases, java.util.HashMap myValueToCount) Calculate the entropy with the given value counts.
protected void	calcEntropyC() Calculates the entropy over the solutions of all the cases.
protected double	calcEntropyOnSubset(FeatureKey key, java.lang.String attributeValue, java.util.LinkedList remainingCases) Calculate the entropy of the set of cases where the attribute specified by key has value attributeValue.
protected double	calcGain(FeatureKey key)
protected double	calcGainRatio(FeatureKey key)
protected void	calcGainRatios()
protected void	calcGains() Calculates the gain for each problem attribute in the domain, as a HashMap mapping FeatureKey to the gain (a Double).
protected double	calcSplitInfo(FeatureKey key)
protected void	eraseCalculations() Destroy the old calculations.
double	getEntropy()
double	getGain(FeatureKey key)
double	getGainRatio(FeatureKey key)
java.util.HashMap	getGainRatios()
java.util.HashMap	getGains()
FeatureKey	getMaxGainKey()
FeatureKey	getMaxGainRatioKey()
protected void	init(Domain domain, java.util.HashSet allKeys)
protected void	reinitCounts() Reinitialize the counts of occurrences of attribute values, to handle a new list of cases.
void	setCases(java.util.ArrayList cases) Reset the state of the InformationTheory object for a new list of cases.
void	setCases(java.util.ArrayList cases, java.util.HashSet keysOfInterest) Reset the state of the InformationTheory object for a new list of cases.
java.lang.String	toString()
protected void	updateCounts()

Methods inherited from class java.lang.Object

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

Field Detail

domain

protected Domain domain

solutionFeatureKey

protected FeatureKey solutionFeatureKey

solutionFeatureSpec

protected FeatureSpec solutionFeatureSpec

allKeys

protected java.util.HashSet allKeys

cases

protected java.util.ArrayList cases

keysOfInterest

protected java.util.HashSet keysOfInterest

probKeyToCountMap

protected KeyToValueToDouble probKeyToCountMap

solValueToCount

protected java.util.HashMap solValueToCount

entropyC

protected double entropyC

keyToGain

protected java.util.HashMap keyToGain

keyToGainRatio

protected java.util.HashMap keyToGainRatio

maxGainKey

protected FeatureKey maxGainKey

maxGainRatioKey

protected FeatureKey maxGainRatioKey

Constructor Detail

InformationTheory

public InformationTheory(Domain domain)

Creates a new instance of InformationTheory. allKeys will be calculated from the domain, as all problem FeatureKeys.

InformationTheory

public InformationTheory(Domain domain,
                         java.util.HashSet allKeys)

Creates a new instance of InformationTheory

Parameters:

allKeys - the maximal set of keys that will ever be considered

Method Detail

init

protected void init(Domain domain,
                    java.util.HashSet allKeys)

setCases

public void setCases(java.util.ArrayList cases,
                     java.util.HashSet keysOfInterest)

Reset the state of the InformationTheory object for a new list of cases.

Parameters:

keysOfInterest - The FeatureKeys corresponding to problem features to be considered.

setCases

public void setCases(java.util.ArrayList cases)

Reset the state of the InformationTheory object for a new list of cases. All problem features are considered.

getEntropy

public double getEntropy()

Returns:

The entropy over the solutions of the cases.

getGains

public java.util.HashMap getGains()

Returns:

HashMap mapping FeatureKey to gain for that feature.

getGain

public double getGain(FeatureKey key)

getMaxGainKey

public FeatureKey getMaxGainKey()

getGainRatios

public java.util.HashMap getGainRatios()

Returns:

HashMap mapping FeatureKey to gain ratio for that feature.

getGainRatio

public double getGainRatio(FeatureKey key)

getMaxGainRatioKey

public FeatureKey getMaxGainRatioKey()

eraseCalculations

protected void eraseCalculations()

Destroy the old calculations. They will be recomputed if their values are requested.

reinitCounts

protected void reinitCounts()

Reinitialize the counts of occurrences of attribute values, to handle a new list of cases. Called by updateCounts().

updateCounts

protected void updateCounts()

calcEntropyC

protected void calcEntropyC()

Calculates the entropy over the solutions of all the cases.

calcEntropy

public double calcEntropy(int numCases,
                          java.util.HashMap myValueToCount)

Calculate the entropy with the given value counts.

Parameters:

myValueToCount - maps feature value (String) to count (Double)

calcGains

protected void calcGains()

Calculates the gain for each problem attribute in the domain, as a HashMap mapping FeatureKey to the gain (a Double).

calcGain

protected double calcGain(FeatureKey key)

calcEntropyOnSubset

protected double calcEntropyOnSubset(FeatureKey key,
                                     java.lang.String attributeValue,
                                     java.util.LinkedList remainingCases)

Calculate the entropy of the set of cases where the attribute specified by key has value attributeValue. Returns 0 if there are no such cases.

calcGainRatios

protected void calcGainRatios()

calcGainRatio

protected double calcGainRatio(FeatureKey key)

calcSplitInfo

protected double calcSplitInfo(FeatureKey key)

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object