weka.classifiers.rules
Class Prism

java.lang.Object
  weka.classifiers.Classifier
      weka.classifiers.rules.Prism

All Implemented Interfaces:

java.lang.Cloneable, OptionHandler, java.io.Serializable

public class Prism

extends Classifier

Class for building and using a PRISM rule set for classifcation. Can only deal with nominal attributes. Can't deal with missing values. Doesn't do any pruning. For more information, see

J. Cendrowska (1987). PRISM: An algorithm for inducing modular rules. International Journal of Man-Machine Studies. Vol.27, No.4, pp.349-370.

Version:

$Revision: 1.16 $

Author:

Ian H. Witten (ihw@cs.waikato.ac.nz)

See Also:

Serialized Form

Nested Class Summary

private class	Prism.PrismRule Class for storing a PRISM ruleset, i.e. a list of rules
private class	Prism.Test Class for storing a list of attribute-value tests

Field Summary

private Prism.PrismRule

m_rules The first rule in the list of rules

Fields inherited from class weka.classifiers.Classifier

m_Debug

Constructor Summary

Prism()

Method Summary

private Prism.PrismRule	addRule(Prism.PrismRule lastRule, Prism.PrismRule newRule) Add a rule to the ruleset.
private Prism.Test	addTest(Prism.PrismRule rule, Prism.Test lastTest, Prism.Test newTest) Add a test to this rule.
void	buildClassifier(Instances data) Generates the classifier.
double	classifyInstance(Instance inst) Classifies a given instance.
private static boolean	contains(Instances E, int C) Does E contain any examples in the class C?
java.lang.String	globalInfo() Returns a string describing classifier
private static boolean	isMentionedIn(Attribute attr, Prism.Test t) Is this attribute mentioned in the rule?
static void	main(java.lang.String[] args) Main method for testing this class
java.lang.String	toString() Prints a description of the classifier.

Methods inherited from class weka.classifiers.Classifier

debugTipText, distributionForInstance, forName, getDebug, getOptions, listOptions, makeCopies, setDebug, setOptions

Methods inherited from class java.lang.Object

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

Field Detail

m_rules

private Prism.PrismRule m_rules

The first rule in the list of rules

Constructor Detail

Prism

public Prism()

Method Detail

globalInfo

public java.lang.String globalInfo()

Returns a string describing classifier

Returns:

a description suitable for displaying in the explorer/experimenter gui

classifyInstance

public double classifyInstance(Instance inst)

Classifies a given instance.

Overrides:

classifyInstance in class Classifier

Parameters:

inst - the instance to be classified

Returns:

the classification

buildClassifier

public void buildClassifier(Instances data)
                     throws java.lang.Exception

Generates the classifier.

Specified by:

buildClassifier in class Classifier

Parameters:

data - the data to be used

Throws:

java.lang.Exception - if the classifier can't built successfully

addRule

private Prism.PrismRule addRule(Prism.PrismRule lastRule,
                                Prism.PrismRule newRule)

Add a rule to the ruleset.

Parameters:

lastRule - the last rule in the rule set

newRule - the rule to be added

Returns:

the new last rule in the rule set

addTest

private Prism.Test addTest(Prism.PrismRule rule,
                           Prism.Test lastTest,
                           Prism.Test newTest)

Add a test to this rule.

Parameters:

rule - the rule to which test is to be added

lastTest - the rule's last test

newTest - the test to be added

Returns:

the new last test of the rule

contains

private static boolean contains(Instances E,
                                int C)
                         throws java.lang.Exception

Does E contain any examples in the class C?

Parameters:

E - the instances to be checked

C - the class

Returns:

true if there are any instances of class C

Throws:

java.lang.Exception

isMentionedIn

private static boolean isMentionedIn(Attribute attr,
                                     Prism.Test t)

Is this attribute mentioned in the rule?

Parameters:

attr - the attribute to be checked for

t - test contained by rule

toString

public java.lang.String toString()

Prints a description of the classifier.

Returns:

a description of the classifier as a string

main

public static void main(java.lang.String[] args)

Main method for testing this class