weka.classifiers.bayes

Class NaiveBayesMultinomialUpdateable

java.lang.Object

weka.classifiers.AbstractClassifier

weka.classifiers.bayes.NaiveBayesMultinomial

weka.classifiers.bayes.NaiveBayesMultinomialUpdateable

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, Classifier, UpdateableClassifier, BatchPredictor, CapabilitiesHandler, CapabilitiesIgnorer, CommandlineRunnable, OptionHandler, RevisionHandler, TechnicalInformationHandler, WeightedInstancesHandler

public class NaiveBayesMultinomialUpdateable
extends NaiveBayesMultinomial
implements UpdateableClassifier

Class for building and using an updateable multinomial Naive Bayes classifier. For more information see,

Andrew Mccallum, Kamal Nigam: A Comparison of Event Models for Naive Bayes Text Classification. In: AAAI-98 Workshop on 'Learning for Text Categorization', 1998.

The core equation for this classifier:

P[Ci|D] = (P[D|Ci] x P[Ci]) / P[D] (Bayes rule)

where Ci is class i and D is a document.

BibTeX:

 @inproceedings{Mccallum1998,
    author = {Andrew Mccallum and Kamal Nigam},
    booktitle = {AAAI-98 Workshop on 'Learning for Text Categorization'},
    title = {A Comparison of Event Models for Naive Bayes Text Classification},
    year = {1998}
 }
 

Valid options are:

-output-debug-info
If set, classifier is run in debug mode and may output additional info to the console.

-do-not-check-capabilities
If set, classifier capabilities are not checked before classifier is built (use with caution).

-num-decimal-laces
The number of decimal places for the output of numbers in the model.

-batch-size
The desired batch size for batch prediction.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected double[]	m_wordsPerClass the number of words per class.

Fields inherited from class weka.classifiers.bayes.NaiveBayesMultinomial

m_headerInfo, m_numAttributes, m_numClasses, m_probOfClass, m_probOfWordGivenClass

Fields inherited from class weka.classifiers.AbstractClassifier

BATCH_SIZE_DEFAULT, m_BatchSize, m_Debug, m_DoNotCheckCapabilities, m_numDecimalPlaces, NUM_DECIMAL_PLACES_DEFAULT

Constructor Summary

Constructors

Constructor and Description
NaiveBayesMultinomialUpdateable()

Method Summary

Modifier and Type	Method and Description
void	buildClassifier(Instances instances) Generates the classifier.
java.lang.String	getRevision() Returns the revision string.
java.lang.String	globalInfo() Returns a string describing this classifier
static void	main(java.lang.String[] argv) Main method for testing this class.
protected double	probOfDocGivenClass(Instance inst, int classIndex) log(N!)
java.lang.String	toString() Returns a string representation of the classifier.
void	updateClassifier(Instance instance) Updates the classifier with information from one training instance.

Methods inherited from class weka.classifiers.bayes.NaiveBayesMultinomial

distributionForInstance, getCapabilities, getTechnicalInformation, initializeClassifier

Methods inherited from class weka.classifiers.AbstractClassifier

batchSizeTipText, classifyInstance, debugTipText, distributionsForInstances, doNotCheckCapabilitiesTipText, forName, getBatchSize, getDebug, getDoNotCheckCapabilities, getNumDecimalPlaces, getOptions, implementsMoreEfficientBatchPrediction, listOptions, makeCopies, makeCopy, numDecimalPlacesTipText, postExecution, preExecution, run, runClassifier, setBatchSize, setDebug, setDoNotCheckCapabilities, setNumDecimalPlaces, setOptions

Methods inherited from class java.lang.Object

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

Field Detail

m_wordsPerClass

protected double[] m_wordsPerClass

the number of words per class.

Constructor Detail

NaiveBayesMultinomialUpdateable

public NaiveBayesMultinomialUpdateable()

Method Detail

globalInfo

public java.lang.String globalInfo()

Returns a string describing this classifier

Overrides:

globalInfo in class NaiveBayesMultinomial

Returns:

a description of the classifier suitable for displaying in the explorer/experimenter gui

buildClassifier

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

Generates the classifier.

Specified by:

buildClassifier in interface Classifier

Overrides:

buildClassifier in class NaiveBayesMultinomial

Parameters:

instances - set of instances serving as training data

Throws:

java.lang.Exception - if the classifier has not been generated successfully

updateClassifier

public void updateClassifier(Instance instance)
                      throws java.lang.Exception

Updates the classifier with information from one training instance.

Specified by:

updateClassifier in interface UpdateableClassifier

Parameters:

instance - the instance to be incorporated

Throws:

java.lang.Exception - if the instance cannot be processed successfully.

probOfDocGivenClass

protected double probOfDocGivenClass(Instance inst,
                                     int classIndex)

log(N!) + (sum for all the words i)(log(Pi^ni) - log(ni!)) where N is the total number of words Pi is the probability of obtaining word i ni is the number of times the word at index i occurs in the document Actually, this method just computes (sum for all the words i)(log(Pi^ni) because the factorials are irrelevant when posterior class probabilities are computed.

Overrides:

probOfDocGivenClass in class NaiveBayesMultinomial

Parameters:

inst - The instance to be classified

classIndex - The index of the class we are calculating the probability with respect to

Returns:

The log of the probability of the document occuring given the class

toString

public java.lang.String toString()

Returns a string representation of the classifier.

Overrides:

toString in class NaiveBayesMultinomial

Returns:

a string representation of the classifier

getRevision

public java.lang.String getRevision()

Returns the revision string.

Specified by:

getRevision in interface RevisionHandler

Overrides:

getRevision in class NaiveBayesMultinomial

Returns:

the revision

main

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

Main method for testing this class.

Parameters:

argv - the options