weka.classifiers.trees.j48

Class C45Split

java.lang.Object

weka.classifiers.trees.j48.ClassifierSplitModel

weka.classifiers.trees.j48.C45Split

All Implemented Interfaces:

Serializable, Cloneable, RevisionHandler

public class C45Split
extends ClassifierSplitModel

Class implementing a C4.5-type split on an attribute.

Version:

$Revision: 8034 $

Author:

Eibe Frank (eibe@cs.waikato.ac.nz)

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
C45Split(int attIndex, int minNoObj, double sumOfWeights, boolean useMDLcorrection) Initializes the split model.

Method Summary

Methods

Modifier and Type	Method and Description
int	attIndex() Returns index of attribute for which split was generated.
void	buildClassifier(Instances trainInstances) Creates a C4.5-type split on the given data.
double	classProb(int classIndex, Instance instance, int theSubset) Gets class probability for instance.
double	codingCost() Returns coding cost for split (used in rule learner).
double	gainRatio() Returns (C4.5-type) gain ratio for the generated split.
String	getRevision() Returns the revision string.
double	infoGain() Returns (C4.5-type) information gain for the generated split.
String	leftSide(Instances data) Prints left side of condition..
double[][]	minsAndMaxs(Instances data, double[][] minsAndMaxs, int index) Returns the minsAndMaxs of the index.th subset.
void	resetDistribution(Instances data) Sets distribution associated with model.
String	rightSide(int index, Instances data) Prints the condition satisfied by instances in a subset.
void	setSplitPoint(Instances allInstances) Sets split point to greatest value in given data smaller or equal to old split point.
String	sourceExpression(int index, Instances data) Returns a string containing java source code equivalent to the test made at this node.
double	splitPoint() Returns the split point (numeric attribute only).
double[]	weights(Instance instance) Returns weights if instance is assigned to more than one subset.
int	whichSubset(Instance instance) Returns index of subset instance is assigned to.

Methods inherited from class weka.classifiers.trees.j48.ClassifierSplitModel

checkModel, classifyInstance, classProbLaplace, clone, distribution, dumpLabel, dumpModel, numSubsets, sourceClass, split

Methods inherited from class java.lang.Object

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

Constructor Detail

C45Split

public C45Split(int attIndex,
        int minNoObj,
        double sumOfWeights,
        boolean useMDLcorrection)

Initializes the split model.

Method Detail

buildClassifier

public void buildClassifier(Instances trainInstances)
                     throws Exception

Creates a C4.5-type split on the given data. Assumes that none of the class values is missing.

Specified by:

buildClassifier in class ClassifierSplitModel

Throws:

Exception - if something goes wrong

attIndex

public final int attIndex()

Returns index of attribute for which split was generated.

splitPoint

public double splitPoint()

Returns the split point (numeric attribute only).

Returns:

the split point used for a test on a numeric attribute

classProb

public final double classProb(int classIndex,
               Instance instance,
               int theSubset)
                       throws Exception

Gets class probability for instance.

Overrides:

classProb in class ClassifierSplitModel

Throws:

Exception - if something goes wrong

codingCost

public final double codingCost()

Returns coding cost for split (used in rule learner).

Overrides:

codingCost in class ClassifierSplitModel

gainRatio

public final double gainRatio()

Returns (C4.5-type) gain ratio for the generated split.

infoGain

public final double infoGain()

Returns (C4.5-type) information gain for the generated split.

leftSide

public final String leftSide(Instances data)

Prints left side of condition..

Specified by:

leftSide in class ClassifierSplitModel

Parameters:

data - training set.

rightSide

public final String rightSide(int index,
               Instances data)

Prints the condition satisfied by instances in a subset.

Specified by:

rightSide in class ClassifierSplitModel

Parameters:

index - of subset

data - training set.

sourceExpression

public final String sourceExpression(int index,
                      Instances data)

Returns a string containing java source code equivalent to the test made at this node. The instance being tested is called "i".

Specified by:

sourceExpression in class ClassifierSplitModel

Parameters:

index - index of the nominal value tested

data - the data containing instance structure info

Returns:

a value of type 'String'

setSplitPoint

public final void setSplitPoint(Instances allInstances)

Sets split point to greatest value in given data smaller or equal to old split point. (C4.5 does this for some strange reason).

minsAndMaxs

public final double[][] minsAndMaxs(Instances data,
                     double[][] minsAndMaxs,
                     int index)

Returns the minsAndMaxs of the index.th subset.

resetDistribution

public void resetDistribution(Instances data)
                       throws Exception

Sets distribution associated with model.

Overrides:

resetDistribution in class ClassifierSplitModel

Throws:

Exception

weights

public final double[] weights(Instance instance)

Returns weights if instance is assigned to more than one subset. Returns null if instance is only assigned to one subset.

Specified by:

weights in class ClassifierSplitModel

whichSubset

public final int whichSubset(Instance instance)
                      throws Exception

Returns index of subset instance is assigned to. Returns -1 if instance is assigned to more than one subset.

Specified by:

whichSubset in class ClassifierSplitModel

Throws:

Exception - if something goes wrong

getRevision

public String getRevision()

Returns the revision string.

Returns:

the revision