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Class weka.classifiers.adtree.TwoWayNominalSplit

java.lang.Object
   |
   +----weka.classifiers.adtree.Splitter
           |
           +----weka.classifiers.adtree.TwoWayNominalSplit

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'.

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

Constructor Index

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

Method Index

 o attributeString(Instances)
Gets the string describing the attributes the split depends on.
 o branchInstanceGoesDown(Instance)
Gets the index of the branch that an instance applies to.
 o clone()
Clones this node.
 o comparisonString(int, Instances)
Gets the string describing the comparision the split depends on for a particular branch.
 o equalTo(Splitter)
Tests whether two splitters are equivalent.
 o getChildForBranch(int)
Gets the child for a branch of the split.
 o getNumOfBranches()
Gets the number of branches of the split.
 o instancesDownBranch(int, Instances)
Gets the subset of instances that apply to a particluar branch of the split.
 o setChildForBranch(int, PredictionNode)
Sets the child for a branch of the split.

Constructors

 o 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

Methods

 o getNumOfBranches
 public int getNumOfBranches()
Gets the number of branches of the split.

Returns:
the number of branches (always = 2)
Overrides:
getNumOfBranches in class Splitter
 o branchInstanceGoesDown
 public int branchInstanceGoesDown(Instance inst)
Gets the index of the branch that an instance applies to. Returns -1 if no branches apply.

Parameters:
i - the instance
Returns:
the branch index
Overrides:
branchInstanceGoesDown in class Splitter
 o 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.

Parameters:
branch - the index of the branch
sourceInstances - the instances from which to find the subset
Returns:
the set of instances that apply
Overrides:
instancesDownBranch in class Splitter
 o attributeString
 public 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.

Parameters:
dataset - the dataset that the split is based on
Returns:
a string describing the attributes
Overrides:
attributeString in class Splitter
 o comparisonString
 public 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.

Parameters:
branchNum - the branch of the split
dataset - the dataset that the split is based on
Returns:
a string describing the comparison
Overrides:
comparisonString in class Splitter
 o equalTo
 public boolean equalTo(Splitter compare)
Tests whether two splitters are equivalent.

Parameters:
compare - the splitter to compare with
Returns:
whether or not they match
Overrides:
equalTo in class Splitter
 o setChildForBranch
 public void setChildForBranch(int branchNum,
                               PredictionNode childPredictor)
Sets the child for a branch of the split.

Parameters:
branchNum - the branch to set the child for
childPredictor - the new child
Overrides:
setChildForBranch in class Splitter
 o getChildForBranch
 public PredictionNode getChildForBranch(int branchNum)
Gets the child for a branch of the split.

Parameters:
branchNum - the branch to get the child for
Returns:
the child
Overrides:
getChildForBranch in class Splitter
 o clone
 public Object clone()
Clones this node. Performs a deep copy, recursing through the tree.

Returns:
a clone
Overrides:
clone in class Splitter

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