cc.mallet.types

Class GainRatio

java.lang.Object

cc.mallet.types.SparseVector

cc.mallet.types.FeatureVector

cc.mallet.types.RankedFeatureVector

cc.mallet.types.GainRatio

All Implemented Interfaces:

AlphabetCarrying, ConstantMatrix, Vector, java.io.Serializable

public class GainRatio
extends RankedFeatureVector

List of features along with their thresholds sorted in descending order of the ratio of (1) information gained by splitting instances on the feature at its associated threshold value, to (2) the split information.

The calculations performed do not take into consideration the instance weights.

To create an instance of GainRatio from an InstanceList, one must do the following:

InstanceList ilist = ... ... GainRatio gr = GainRatio.createGainRatio(ilist);

J. R. Quinlan "Improved Use of Continuous Attributes in C4.5" ftp://ftp.cs.cmu.edu/project/jair/volume4/quinlan96a.ps

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class cc.mallet.types.RankedFeatureVector

RankedFeatureVector.Factory, RankedFeatureVector.PerLabelFactory

Field Summary

Fields

Modifier and Type	Field and Description
static double	log2

Method Summary

Modifier and Type	Method and Description
static GainRatio	createGainRatio(InstanceList ilist) Constructs a GainRatio object.
static GainRatio	createGainRatio(InstanceList ilist, int[] instIndices, int minNumInsts) Constructs a GainRatio object
double	getBaseEntropy()
LabelVector	getBaseLabelDistribution()
double	getMaxValuedThreshold()
int	getNumSplitPointsForBestFeature()
double	getThresholdAtRank(int rank)
static int[]	sortInstances(InstanceList ilist, int[] instIndices, int featureIndex)

Methods inherited from class cc.mallet.types.RankedFeatureVector

getIndexAtRank, getMaxValue, getMaxValuedIndex, getMaxValuedIndexIn, getMaxValuedObject, getMaxValuedObjectIn, getMaxValueIn, getObjectAtRank, getRank, getRank, getValueAtRank, printByRank, printByRank, printLowerK, printTopK, set

Methods inherited from class cc.mallet.types.FeatureVector

alphabetsMatch, cloneMatrix, cloneMatrixZeroed, contains, getAlphabet, getAlphabets, getObjectIndices, location, newFeatureVector, toSimpFile, toString, toString, value

Methods inherited from class cc.mallet.types.SparseVector

absNorm, addTo, addTo, arrayCopyFrom, arrayCopyFrom, arrayCopyInto, dotProduct, dotProduct, dotProduct, dotProduct, extendedDotProduct, extendedDotProduct, getDimensions, getIndices, getNumDimensions, getValues, incrementValue, indexAtLocation, infinityNorm, isBinary, isInfinite, isNaN, isNaNOrInfinite, location, makeBinary, makeNonBinary, map, numLocations, oneNorm, plusEqualsSparse, plusEqualsSparse, print, setAll, setValue, setValueAtLocation, singleIndex, singleSize, singleToIndices, singleValue, timesEquals, timesEqualsSparse, timesEqualsSparse, timesEqualsSparseZero, twoNorm, value, value, valueAtLocation, vectorAdd

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

log2

public static final double log2

Method Detail

sortInstances

public static int[] sortInstances(InstanceList ilist,
                                  int[] instIndices,
                                  int featureIndex)

createGainRatio

public static GainRatio createGainRatio(InstanceList ilist)

Constructs a GainRatio object.

createGainRatio

public static GainRatio createGainRatio(InstanceList ilist,
                                        int[] instIndices,
                                        int minNumInsts)

Constructs a GainRatio object

getMaxValuedThreshold

public double getMaxValuedThreshold()

Returns:

the threshold of the (feature, threshold) pair with with maximum gain ratio

getThresholdAtRank

public double getThresholdAtRank(int rank)

Returns:

the threshold of the (feature, threshold) pair with the given rank

getBaseEntropy

public double getBaseEntropy()

getBaseLabelDistribution

public LabelVector getBaseLabelDistribution()

getNumSplitPointsForBestFeature

public int getNumSplitPointsForBestFeature()