Package org.apache.lucene.classification

Class BM25NBClassifier

java.lang.Object

org.apache.lucene.classification.BM25NBClassifier

All Implemented Interfaces:

Classifier<BytesRef>

public class BM25NBClassifier
extends Object
implements Classifier<BytesRef>

A classifier approximating naive bayes classifier by using pure queries on BM25.

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

Constructor Summary

Constructors

Constructor	Description
BM25NBClassifier(IndexReader indexReader, Analyzer analyzer, Query query, String classFieldName, String... textFieldNames)	Creates a new NaiveBayes classifier.

Method Summary

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

BM25NBClassifier

public BM25NBClassifier(IndexReader indexReader,
                        Analyzer analyzer,
                        Query query,
                        String classFieldName,
                        String... textFieldNames)

Creates a new NaiveBayes classifier.

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

classFieldName - the name of the field used as the output for the classifier NOTE: must not be heavely analyzed as the returned class will be a token indexed for this field

textFieldNames - the name of the fields used as the inputs for the classifier, NO boosting supported per field

Method Detail

assignClass

public ClassificationResult<BytesRef> assignClass(String inputDocument)
                                           throws IOException

Description copied from interface: Classifier

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

Specified by:

assignClass in interface Classifier<BytesRef>

Parameters:

inputDocument - 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<BytesRef>> getClasses(String text)
                                                throws IOException

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<BytesRef>

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.

Throws:

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

getClasses

public List<ClassificationResult<BytesRef>> getClasses(String text,
                                                       int max)
                                                throws IOException

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<BytesRef>

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.

Throws:

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