Module org.apache.lucene.classification

Package org.apache.lucene.classification

Class KNearestFuzzyClassifier

java.lang.Object

org.apache.lucene.classification.KNearestFuzzyClassifier

All Implemented Interfaces:

Classifier<BytesRef>

public class KNearestFuzzyClassifier
extends Object
implements Classifier<BytesRef>

A k-Nearest Neighbor classifier based on NearestFuzzyQuery.

Field Summary

Fields

Modifier and Type	Field	Description
private final Analyzer	analyzer
private final String	classFieldName	the name of the field used as the output text
private final IndexSearcher	indexSearcher	an IndexSearcher used to perform queries
private final int	k	the no.
private final Query	query	a Query used to filter the documents that should be used from this classifier's underlying LeafReader
private final String[]	textFieldNames	the name of the fields used as the input text

Constructor Summary

Constructors

Constructor	Description
KNearestFuzzyClassifier(IndexReader indexReader, Similarity similarity, Analyzer analyzer, Query query, int k, String classFieldName, String... textFieldNames)	Creates a KNearestFuzzyClassifier.

Method Summary

Modifier and Type	Method	Description
ClassificationResult<BytesRef>	assignClass(String text)	Assign a class (with score) to the given text String
private List<ClassificationResult<BytesRef>>	buildListFromTopDocs(TopDocs topDocs)	build a list of classification results from search results
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.
private TopDocs	knnSearch(String text)
String	toString()

Methods inherited from class java.lang.Object

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

Field Details

textFieldNames

private final String[] textFieldNames

the name of the fields used as the input text

classFieldName

private final String classFieldName

the name of the field used as the output text

indexSearcher

private final IndexSearcher indexSearcher

an IndexSearcher used to perform queries

k

private final int k

the no. of docs to compare in order to find the nearest neighbor to the input text

query

private final Query query

a Query used to filter the documents that should be used from this classifier's underlying LeafReader

analyzer

private final Analyzer analyzer

Constructor Details

KNearestFuzzyClassifier

public KNearestFuzzyClassifier(IndexReader indexReader,
 Similarity similarity,
 Analyzer analyzer,
 Query query,
 int k,
 String classFieldName,
 String... textFieldNames)

Creates a KNearestFuzzyClassifier.

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)

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

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

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

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(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<BytesRef>

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<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.

knnSearch

private TopDocs knnSearch(String text)
                   throws IOException

Throws:

IOException

buildListFromTopDocs

private List<ClassificationResult<BytesRef>> buildListFromTopDocs(TopDocs topDocs)
                                                           throws IOException

build a list of classification results from search results

Parameters:

topDocs - the search results as a TopDocs object

Returns:

a List of ClassificationResult, one for each existing class

Throws:

IOException - if it's not possible to get the stored value of class field

toString

public String toString()

Overrides:

toString in class Object