Package org.apache.lucene.classification.document

Class KNearestNeighborDocumentClassifier

java.lang.Object

org.apache.lucene.classification.KNearestNeighborClassifier

org.apache.lucene.classification.document.KNearestNeighborDocumentClassifier

All Implemented Interfaces:

Classifier<BytesRef>, DocumentClassifier<BytesRef>

public class KNearestNeighborDocumentClassifier
extends KNearestNeighborClassifier
implements DocumentClassifier<BytesRef>

A k-Nearest Neighbor Document classifier (see http://en.wikipedia.org/wiki/K-nearest_neighbors) based on MoreLikeThis .

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

Field Summary

Fields

Modifier and Type	Field	Description
protected final Map<String,Analyzer>	field2analyzer	map of per field analyzers

Fields inherited from class org.apache.lucene.classification.KNearestNeighborClassifier

classFieldName, indexSearcher, k, mlt, query, textFieldNames

Constructor Summary

Constructors

Constructor	Description
KNearestNeighborDocumentClassifier(IndexReader indexReader, Similarity similarity, Query query, int k, int minDocsFreq, int minTermFreq, String classFieldName, Map<String,Analyzer> field2analyzer, String... textFieldNames)	Creates a KNearestNeighborClassifier.

Method Summary

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

Methods inherited from class org.apache.lucene.classification.KNearestNeighborClassifier

assignClass, buildListFromTopDocs, classifyFromTopDocs, getClasses, getClasses, toString

Methods inherited from class java.lang.Object

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

Field Details

field2analyzer

protected final Map<String,Analyzer> field2analyzer

map of per field analyzers

Constructor Details

KNearestNeighborDocumentClassifier

public KNearestNeighborDocumentClassifier(IndexReader indexReader,
 Similarity similarity,
 Query query,
 int k,
 int minDocsFreq,
 int minTermFreq,
 String classFieldName,
 Map<String,Analyzer> field2analyzer,
 String... textFieldNames)

Creates a KNearestNeighborClassifier.

Parameters:

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

similarity - the Similarity to be used by the underlying IndexSearcher or null (defaults to BM25Similarity)

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

k - the no. of docs to select in the MLT results to find the nearest neighbor

minDocsFreq - MoreLikeThis.minDocFreq parameter

minTermFreq - MoreLikeThis.minTermFreq parameter

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

field2analyzer - map with key a field name and the related {org.apache.lucene.analysis.Analyzer}

textFieldNames - the name of the fields used as the inputs for the classifier, they can contain boosting indication e.g. title^10

Method Details

assignClass

public ClassificationResult<BytesRef> assignClass(Document document)
                                           throws IOException

Description copied from interface: DocumentClassifier

Assign a class (with score) to the given Document

Specified by:

assignClass in interface DocumentClassifier<BytesRef>

Parameters:

document - a Document to be classified. Fields are considered features for the classification.

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(Document document)
                                                throws IOException

Description copied from interface: DocumentClassifier

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

Specified by:

getClasses in interface DocumentClassifier<BytesRef>

Parameters:

document - a Document to be classified. Fields are considered features for the classification.

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(Document document,
 int max)
                                                throws IOException

Description copied from interface: DocumentClassifier

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

Specified by:

getClasses in interface DocumentClassifier<BytesRef>

Parameters:

document - a Document to be classified. Fields are considered features for the classification.

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.