weka.classifiers.trees.adtree
Class TwoWayNominalSplit

java.lang.Object
  weka.classifiers.trees.adtree.Splitter
      weka.classifiers.trees.adtree.TwoWayNominalSplit

All Implemented Interfaces:

java.lang.Cloneable, java.io.Serializable

public class TwoWayNominalSplit

extends Splitter

Class representing a two-way split on a nominal attribute, of the form: either 'is some_value' or 'is not some_value'.

Version:

$Revision: 1.2 $

Author:

Richard Kirkby (rkirkby@cs.waikato.ac.nz)

See Also:

Serialized Form

Field Summary

private int	attIndex The index of the attribute the split depends on
private PredictionNode[]	children The children of this split
private int	trueSplitValue The attribute value that is compared against

Fields inherited from class weka.classifiers.trees.adtree.Splitter

orderAdded

Constructor Summary

TwoWayNominalSplit(int _attIndex, int _trueSplitValue)
Creates a new two-way nominal splitter.

Method Summary

java.lang.String	attributeString(Instances dataset) Gets the string describing the attributes the split depends on.
int	branchInstanceGoesDown(Instance inst) Gets the index of the branch that an instance applies to.
java.lang.Object	clone() Clones this node.
java.lang.String	comparisonString(int branchNum, Instances dataset) Gets the string describing the comparision the split depends on for a particular branch. i.e. the right hand side of the description of the split.
boolean	equalTo(Splitter compare) Tests whether two splitters are equivalent.
PredictionNode	getChildForBranch(int branchNum) Gets the child for a branch of the split.
int	getNumOfBranches() Gets the number of branches of the split.
ReferenceInstances	instancesDownBranch(int branch, Instances instances) Gets the subset of instances that apply to a particluar branch of the split.
void	setChildForBranch(int branchNum, PredictionNode childPredictor) Sets the child for a branch of the split.

Methods inherited from class java.lang.Object

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

Field Detail

attIndex

private int attIndex

The index of the attribute the split depends on

trueSplitValue

private int trueSplitValue

The attribute value that is compared against

children

private PredictionNode[] children

The children of this split

Constructor Detail

TwoWayNominalSplit

public TwoWayNominalSplit(int _attIndex,
                          int _trueSplitValue)

Creates a new two-way nominal splitter.

Parameters:

_attIndex - the index of the attribute this split depeneds on

_trueSplitValue - the attribute value that the splitter splits on

Method Detail

getNumOfBranches

public int getNumOfBranches()

Gets the number of branches of the split.

Specified by:

getNumOfBranches in class Splitter

Returns:

the number of branches (always = 2)

branchInstanceGoesDown

public int branchInstanceGoesDown(Instance inst)

Gets the index of the branch that an instance applies to. Returns -1 if no branches apply.

Specified by:

branchInstanceGoesDown in class Splitter

Parameters:

inst - the instance

Returns:

the branch index

instancesDownBranch

public ReferenceInstances instancesDownBranch(int branch,
                                              Instances instances)

Gets the subset of instances that apply to a particluar branch of the split. If the branch index is -1, the subset will consist of those instances that don't apply to any branch.

Specified by:

instancesDownBranch in class Splitter

Parameters:

branch - the index of the branch

instances - the instances from which to find the subset

Returns:

the set of instances that apply

attributeString

public java.lang.String attributeString(Instances dataset)

Gets the string describing the attributes the split depends on. i.e. the left hand side of the description of the split.

Specified by:

attributeString in class Splitter

Parameters:

dataset - the dataset that the split is based on

Returns:

a string describing the attributes

comparisonString

public java.lang.String comparisonString(int branchNum,
                                         Instances dataset)

Gets the string describing the comparision the split depends on for a particular branch. i.e. the right hand side of the description of the split.

Specified by:

comparisonString in class Splitter

Parameters:

branchNum - the branch of the split

dataset - the dataset that the split is based on

Returns:

a string describing the comparison

equalTo

public boolean equalTo(Splitter compare)

Tests whether two splitters are equivalent.

Specified by:

equalTo in class Splitter

Parameters:

compare - the splitter to compare with

Returns:

whether or not they match

setChildForBranch

public void setChildForBranch(int branchNum,
                              PredictionNode childPredictor)

Sets the child for a branch of the split.

Specified by:

setChildForBranch in class Splitter

Parameters:

branchNum - the branch to set the child for

childPredictor - the new child

getChildForBranch

public PredictionNode getChildForBranch(int branchNum)

Gets the child for a branch of the split.

Specified by:

getChildForBranch in class Splitter

Parameters:

branchNum - the branch to get the child for

Returns:

the child

clone

public java.lang.Object clone()

Clones this node. Performs a deep copy, recursing through the tree.

Specified by:

clone in class Splitter

Returns:

a clone