weka.classifiers.rules
Class JRip

java.lang.Object
  |
  +--weka.classifiers.Classifier
        |
        +--weka.classifiers.rules.JRip

All Implemented Interfaces:

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

public class JRip

extends Classifier

implements OptionHandler, AdditionalMeasureProducer, WeightedInstancesHandler

This class implements a propositional rule learner, Repeated Incremental Pruning to Produce Error Reduction (RIPPER), which is proposed by William W. Cohen as an optimized version of IREP.

The algorithm is briefly described as follows:

Initialize RS = {}, and for each class from the less prevalent one to the more frequent one, DO:

1. Building stage: repeat 1.1 and 1.2 until the descrition length (DL) of the ruleset and examples is 64 bits greater than the smallest DL met so far, or there are no positive examples, or the error rate >= 50%.

1.1. Grow phase:
Grow one rule by greedily adding antecedents (or conditions) to the rule until the rule is perfect (i.e. 100% accurate). The procedure tries every possible value of each attribute and selects the condition with highest information gain: p(log(p/t)-log(P/T)).

1.2. Prune phase:
Incrementally prune each rule and allow the pruning of any final sequences of the antecedents;
The pruning metric is (p-n)/(p+n) -- but it's actually 2p/(p+n) -1, so in this implementation we simply use p/(p+n) (actually (p+1)/(p+n+2), thus if p+n is 0, it's 0.5).

2. Optimization stage: after generating the initial ruleset {Ri}, generate and prune two variants of each rule Ri from randomized data using procedure 1.1 and 1.2. But one variant is generated from an empty rule while the other is generated by greedily adding antecedents to the original rule. Moreover, the pruning metric used here is (TP+TN)/(P+N).
Then the smallest possible DL for each variant and the original rule is computed. The variant with the minimal DL is selected as the final representative of Ri in the ruleset.
After all the rules in {Ri} have been examined and if there are still residual positives, more rules are generated based on the residual positives using Building Stage again.

3. Delete the rules from the ruleset that would increase the DL of the whole ruleset if it were in it. and add resultant ruleset to RS.

ENDDO

Note that there seem to be 2 bugs in the ripper program that would affect the ruleset size and accuracy slightly. This implementation avoids these bugs and thus is a little bit different from Cohen's original implementation. Even after fixing the bugs, since the order of classes with the same frequency is not defined in ripper, there still seems to be some trivial difference between this implementation and the original ripper, especially for audiology data in UCI repository, where there are lots of classes of few instances.

If wrapped by other classes, typical usage of this class is:
JRip rip = new JRip(); Instances data = ... // Data from somewhere double[] orderedClasses = ... // Get the ordered class counts for the data double expFPRate = ... // Calculate the expected FP/(FP+FN) rate double classIndex = ... // The class index for which ruleset is built // DL of default rule, no theory DL, only data DL double defDL = RuleStats.dataDL(expFPRate, 0.0, data.sumOfWeights(), 0.0, orderedClasses[(int)classIndex]); rip.rulesetForOneClass(expFPRate, data, classIndex, defDL); RuleStats rulesetStats = rip.getRuleStats(0); // Can get heaps of information from RuleStats, e.g. combined DL, // simpleStats, etc. double comDL = rulesetStats.combinedDL(expFPRate, classIndex); int whichRule = ... // Want simple stats of which rule? double[] simpleStats = rulesetStats.getSimpleStats(whichRule); ... Details please see "Fast Effective Rule Induction", William W. Cohen, 'Machine Learning: Proceedings of the Twelfth International Conference' (ML95).

PS. We have compared this implementation with the original ripper implementation in aspects of accuracy, ruleset size and running time on both artificial data "ab+bcd+defg" and UCI datasets. In all these aspects it seems to be quite comparable to the original ripper implementation. However, we didn't consider memory consumption optimization in this implementation.

Version:

$Revision: 1.13 $

Author:

Xin Xu (xx5@cs.waikato.ac.nz), Eibe Frank (eibe@cs.waikato.ac.nz)

See Also:

Serialized Form

Constructor Summary

JRip()

Method Summary

void	buildClassifier(Instances instances) Builds Ripper in the order of class frequencies.
java.lang.String	checkErrorRateTipText() Returns the tip text for this property
java.lang.String	debugTipText() Returns the tip text for this property
double[]	distributionForInstance(Instance datum) Classify the test instance with the rule learner and provide the class distributions
java.util.Enumeration	enumerateMeasures() Returns an enumeration of the additional measure names
java.lang.String	foldsTipText() Returns the tip text for this property
boolean	getCheckErrorRate()
boolean	getDebug() Get whether debugging is turned on.
int	getFolds()
double	getMeasure(java.lang.String additionalMeasureName) Returns the value of the named measure
double	getMinNo()
int	getOptimizations()
java.lang.String[]	getOptions() Gets the current settings of the Classifier.
FastVector	getRuleset() Get the ruleset generated by Ripper
RuleStats	getRuleStats(int pos) Get the statistics of the ruleset in the given position
long	getSeed()
boolean	getUsePruning()
java.lang.String	globalInfo() Returns a string describing classifier
java.util.Enumeration	listOptions() Returns an enumeration describing the available options Valid options are:
static void	main(java.lang.String[] args) Main method.
java.lang.String	minNoTipText() Returns the tip text for this property
java.lang.String	optimizationsTipText() Returns the tip text for this property
java.lang.String	seedTipText() Returns the tip text for this property
void	setCheckErrorRate(boolean d)
void	setDebug(boolean d) Set debugging mode.
void	setFolds(int fold)
void	setMinNo(double m)
void	setOptimizations(int run)
void	setOptions(java.lang.String[] options) Parses a given list of options.
void	setSeed(long s)
void	setUsePruning(boolean d)
java.lang.String	toString() Prints the all the rules of the rule learner.
java.lang.String	usePruningTipText() Returns the tip text for this property

Methods inherited from class weka.classifiers.Classifier

classifyInstance, forName, makeCopies

Methods inherited from class java.lang.Object

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

Constructor Detail

JRip

public JRip()

Method Detail

globalInfo

public java.lang.String globalInfo()

Returns a string describing classifier

Returns:

a description suitable for displaying in the explorer/experimenter gui

listOptions

public java.util.Enumeration listOptions()

Returns an enumeration describing the available options Valid options are:

-F number
The number of folds for reduced error pruning. One fold is used as the pruning set. (Default: 3)

-N number
The minimal weights of instances within a split. (Default: 2)

-O number
Set the number of runs of optimizations. (Default: 2)

-D
Whether turn on the debug mode -S number
The seed of randomization used in Ripper.(Default: 1)

-E
Whether NOT check the error rate >= 0.5 in stopping criteria. (default: check)

-P
Whether NOT use pruning. (default: use pruning)

Specified by:

listOptions in interface OptionHandler

Overrides:

listOptions in class Classifier

Returns:

an enumeration of all the available options

setOptions

public void setOptions(java.lang.String[] options)
                throws java.lang.Exception

Parses a given list of options.

Specified by:

setOptions in interface OptionHandler

Overrides:

setOptions in class Classifier

Parameters:

options - the list of options as an array of strings

Throws:

java.lang.Exception - if an option is not supported

getOptions

public java.lang.String[] getOptions()

Gets the current settings of the Classifier.

Specified by:

getOptions in interface OptionHandler

Overrides:

getOptions in class Classifier

Returns:

an array of strings suitable for passing to setOptions

enumerateMeasures

public java.util.Enumeration enumerateMeasures()

Returns an enumeration of the additional measure names

Specified by:

enumerateMeasures in interface AdditionalMeasureProducer

Returns:

an enumeration of the measure names

getMeasure

public double getMeasure(java.lang.String additionalMeasureName)

Returns the value of the named measure

Specified by:

getMeasure in interface AdditionalMeasureProducer

Parameters:

additionalMeasureName - the name of the measure to query for its value

Returns:

the value of the named measure

Throws:

java.lang.IllegalArgumentException - if the named measure is not supported

foldsTipText

public java.lang.String foldsTipText()

Returns the tip text for this property

Returns:

tip text for this property suitable for displaying in the explorer/experimenter gui

setFolds

public void setFolds(int fold)

getFolds

public int getFolds()

minNoTipText

public java.lang.String minNoTipText()

Returns the tip text for this property

Returns:

tip text for this property suitable for displaying in the explorer/experimenter gui

setMinNo

public void setMinNo(double m)

getMinNo

public double getMinNo()

seedTipText

public java.lang.String seedTipText()

Returns the tip text for this property

Returns:

tip text for this property suitable for displaying in the explorer/experimenter gui

setSeed

public void setSeed(long s)

getSeed

public long getSeed()

optimizationsTipText

public java.lang.String optimizationsTipText()

Returns the tip text for this property

Returns:

tip text for this property suitable for displaying in the explorer/experimenter gui

setOptimizations

public void setOptimizations(int run)

getOptimizations

public int getOptimizations()

debugTipText

public java.lang.String debugTipText()

Returns the tip text for this property

Overrides:

debugTipText in class Classifier

Returns:

tip text for this property suitable for displaying in the explorer/experimenter gui

setDebug

public void setDebug(boolean d)

Description copied from class: Classifier

Set debugging mode.

Overrides:

setDebug in class Classifier

Parameters:

d - true if debug output should be printed

getDebug

public boolean getDebug()

Description copied from class: Classifier

Get whether debugging is turned on.

Overrides:

getDebug in class Classifier

Returns:

true if debugging output is on

checkErrorRateTipText

public java.lang.String checkErrorRateTipText()

Returns the tip text for this property

Returns:

tip text for this property suitable for displaying in the explorer/experimenter gui

setCheckErrorRate

public void setCheckErrorRate(boolean d)

getCheckErrorRate

public boolean getCheckErrorRate()

usePruningTipText

public java.lang.String usePruningTipText()

Returns the tip text for this property

Returns:

tip text for this property suitable for displaying in the explorer/experimenter gui

setUsePruning

public void setUsePruning(boolean d)

getUsePruning

public boolean getUsePruning()

getRuleset

public FastVector getRuleset()

Get the ruleset generated by Ripper

Returns:

the ruleset

getRuleStats

public RuleStats getRuleStats(int pos)

Get the statistics of the ruleset in the given position

Parameters:

pos - the position of the stats, assuming correct

buildClassifier

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

Builds Ripper in the order of class frequencies. For each class it's built in two stages: building and optimization

Specified by:

buildClassifier in class Classifier

Parameters:

instances - the training data

Throws:

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

distributionForInstance

public double[] distributionForInstance(Instance datum)

Classify the test instance with the rule learner and provide the class distributions

Overrides:

distributionForInstance in class Classifier

Parameters:

datum - the instance to be classified

Returns:

the distribution

toString

public java.lang.String toString()

Prints the all the rules of the rule learner.

Overrides:

toString in class java.lang.Object

Returns:

a textual description of the classifier

main

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

Main method.

Parameters:

args - the options for the classifier