Package org.apache.lucene.classification

Class BooleanPerceptronClassifier

java.lang.Object

org.apache.lucene.classification.BooleanPerceptronClassifier

All Implemented Interfaces:

Classifier<Boolean>

public class BooleanPerceptronClassifier
extends Object
implements Classifier<Boolean>

A perceptron (see http://en.wikipedia.org/wiki/Perceptron) based Boolean Classifier. The weights are calculated using TermsEnum.totalTermFreq() both on a per field and a per document basis and then a corresponding FST is used for class assignment.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Constructor Summary

Constructors

Constructor	Description
BooleanPerceptronClassifier(IndexReader indexReader, Analyzer analyzer, Query query, Integer batchSize, Double bias, String classFieldName, String textFieldName)	Creates a BooleanPerceptronClassifier

Method Summary

Modifier and Type	Method	Description
ClassificationResult<Boolean>	assignClass(String text)	Assign a class (with score) to the given text String
List<ClassificationResult<Boolean>>	getClasses(String text)	Get all the classes (sorted by score, descending) assigned to the given text String.
List<ClassificationResult<Boolean>>	getClasses(String text, int max)	Get the first max classes (sorted by score, descending) assigned to the given text String.

Methods inherited from class java.lang.Object

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

Constructor Details

BooleanPerceptronClassifier

public BooleanPerceptronClassifier(IndexReader indexReader,
 Analyzer analyzer,
 Query query,
 Integer batchSize,
 Double bias,
 String classFieldName,
 String textFieldName)
                            throws IOException

Creates a BooleanPerceptronClassifier

Parameters:

indexReader - the reader on the index to be used for classification

analyzer - an Analyzer used to analyze unseen text

query - a Query to eventually filter the docs used for training the classifier, or null if all the indexed docs should be used

batchSize - the size of the batch of docs to use for updating the perceptron weights

bias - the bias used for class separation

classFieldName - the name of the field used as the output for the classifier

textFieldName - the name of the field used as input for the classifier

Throws:

IOException - if the building of the underlying FST fails and / or TermsEnum for the text field cannot be found

Method Details

assignClass

public ClassificationResult<Boolean> assignClass(String text)
                                          throws IOException

Description copied from interface: Classifier

Assign a class (with score) to the given text String

Specified by:

assignClass in interface Classifier<Boolean>

Parameters:

text - a String containing text to be classified

Returns:

a ClassificationResult holding assigned class of type T and score

Throws:

IOException - If there is a low-level I/O error.

getClasses

public List<ClassificationResult<Boolean>> getClasses(String text)

Description copied from interface: Classifier

Get all the classes (sorted by score, descending) assigned to the given text String.

Specified by:

getClasses in interface Classifier<Boolean>

Parameters:

text - a String containing text to be classified

Returns:

the whole list of ClassificationResult, the classes and scores. Returns null if the classifier can't make lists.

getClasses

public List<ClassificationResult<Boolean>> getClasses(String text,
 int max)

Description copied from interface: Classifier

Get the first max classes (sorted by score, descending) assigned to the given text String.

Specified by:

getClasses in interface Classifier<Boolean>

Parameters:

text - a String containing text to be classified

max - the number of return list elements

Returns:

the whole list of ClassificationResult, the classes and scores. Cut for "max" number of elements. Returns null if the classifier can't make lists.