weka.clusterers

Class Cobweb.CNode

java.lang.Object

weka.clusterers.Cobweb.CNode

All Implemented Interfaces:

java.io.Serializable, RevisionHandler

Enclosing class:

Cobweb

public class Cobweb.CNode
extends java.lang.Object
implements java.io.Serializable, RevisionHandler

Inner class handling node operations for Cobweb.

See Also:

Serializable, Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected Instances	m_clusterInstances Instances at this node

Constructor Summary

Constructors

Constructor and Description
CNode(int numAttributes) Creates an empty CNode instance.
CNode(int numAttributes, Instance leafInstance) Creates a new leaf CNode instance.

Method Summary

Modifier and Type	Method and Description
protected void	addChildNode(Cobweb.CNode child) Adds the supplied node as a child of this node.
protected void	addInstance(Instance newInstance) Adds an instance to this cluster.
protected double	categoryUtility() Computes the utility of all children with respect to this node
protected double	categoryUtilityChild(Cobweb.CNode child) Computes the utility of a single child with respect to this node
protected java.lang.String	dumpData() Returns the instances at this node as a string.
protected void	dumpTree(int depth, java.lang.StringBuffer text) Recursively build a string representation of the Cobweb tree
protected double	getProbability(int attIndex, int valueIndex) Returns the probability of a value of a nominal attribute in this node
java.lang.String	getRevision() Returns the revision string.
protected double	getStandardDev(int attIndex) Returns the standard deviation of a numeric attribute
protected void	graphTree(java.lang.StringBuffer text) Recursively generate the graph string for the Cobweb tree.
protected void	updateStats(Instance updateInstance, boolean delete) Update attribute stats using the supplied instance.

Methods inherited from class java.lang.Object

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

Field Detail

m_clusterInstances

protected Instances m_clusterInstances

Instances at this node

Constructor Detail

CNode

public CNode(int numAttributes)

Creates an empty CNode instance.

Parameters:

numAttributes - the number of attributes in the data

CNode

public CNode(int numAttributes,
             Instance leafInstance)

Creates a new leaf CNode instance.

Parameters:

numAttributes - the number of attributes in the data

leafInstance - the instance to store at this leaf

Method Detail

addInstance

protected void addInstance(Instance newInstance)
                    throws java.lang.Exception

Adds an instance to this cluster.

Parameters:

newInstance - the instance to add

Throws:

java.lang.Exception - if an error occurs

addChildNode

protected void addChildNode(Cobweb.CNode child)

Adds the supplied node as a child of this node. All of the child's instances are added to this nodes instances

Parameters:

child - the child to add

categoryUtility

protected double categoryUtility()
                          throws java.lang.Exception

Computes the utility of all children with respect to this node

Returns:

the category utility of the children with respect to this node.

Throws:

java.lang.Exception - if there are no children

categoryUtilityChild

protected double categoryUtilityChild(Cobweb.CNode child)
                               throws java.lang.Exception

Computes the utility of a single child with respect to this node

Parameters:

child - the child for which to compute the utility

Returns:

the utility of the child with respect to this node

Throws:

java.lang.Exception - if something goes wrong

getProbability

protected double getProbability(int attIndex,
                                int valueIndex)
                         throws java.lang.Exception

Returns the probability of a value of a nominal attribute in this node

Parameters:

attIndex - the index of the attribute

valueIndex - the index of the value of the attribute

Returns:

the probability

Throws:

java.lang.Exception - if the requested attribute is not nominal

getStandardDev

protected double getStandardDev(int attIndex)
                         throws java.lang.Exception

Returns the standard deviation of a numeric attribute

Parameters:

attIndex - the index of the attribute

Returns:

the standard deviation

Throws:

java.lang.Exception - if an error occurs

updateStats

protected void updateStats(Instance updateInstance,
                           boolean delete)

Update attribute stats using the supplied instance.

Parameters:

updateInstance - the instance for updating

delete - true if the values of the supplied instance are to be removed from the statistics

dumpTree

protected void dumpTree(int depth,
                        java.lang.StringBuffer text)

Recursively build a string representation of the Cobweb tree

Parameters:

depth - depth of this node in the tree

text - holds the string representation

dumpData

protected java.lang.String dumpData()
                             throws java.lang.Exception

Returns the instances at this node as a string. Appends the cluster number of the child that each instance belongs to.

Returns:

a String value

Throws:

java.lang.Exception - if an error occurs

graphTree

protected void graphTree(java.lang.StringBuffer text)
                  throws java.lang.Exception

Recursively generate the graph string for the Cobweb tree.

Parameters:

text - holds the graph string

Throws:

java.lang.Exception - if generation fails

getRevision

public java.lang.String getRevision()

Returns the revision string.

Specified by:

getRevision in interface RevisionHandler

Returns:

the revision