Package org.terrier.matching.models

Class BM25F

java.lang.Object

org.terrier.matching.models.WeightingModel

org.terrier.matching.models.PerFieldNormWeightingModel

org.terrier.matching.models.BM25F

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, Model

public class BM25F
extends PerFieldNormWeightingModel

A convenience subclass of PerFieldNormWeightingModel setup to do specifically BM25F, as described by [Zaragoza TREC-2004]. [Robertson CIKM-2004] describe a different model, which does not normalise frequencies in a per-field manner.

References:

• [Zaragoza TREC-2004] H. Zaragoza, N. Craswell, M. Taylor, S. Saria, S. Robertson: Microsoft Cambridge at TREC 13: Web and Hard Tracks. In Proc. of TREC 2004.
• [Robertson CIKM-2004] S. Robertson, H. Zaragoza, M. Taylor: Simple BM25 Extension to Multiple Weighted Fields. In Proc. of CIKM 2004.

Since:

3.0

Author:

Craig Macdonald

See Also:

Serialized Form

Field Summary

Fields inherited from class org.terrier.matching.models.PerFieldNormWeightingModel

basicModel, fieldCount, fieldGlobalFrequencies, fieldNormalisations, fieldWeights, params

Fields inherited from class org.terrier.matching.models.WeightingModel

averageDocumentLength, c, cs, documentFrequency, es, i, keyFrequency, numberOfDocuments, numberOfPointers, numberOfPostings, numberOfTokens, numberOfUniqueTerms, rq, termFrequency

Constructor Summary

Constructors

Constructor	Description
BM25F()	Constructs an instance of the BM25F

Method Summary

Modifier and Type	Method	Description
java.lang.String	getInfo()	Returns the name of the model.

Methods inherited from class org.terrier.matching.models.PerFieldNormWeightingModel

clone, prepare, score, score, setCollectionStatistics, setEntryStatistics

Methods inherited from class org.terrier.matching.models.WeightingModel

getOverflowed, getParameter, setKeyFrequency, setParameter, setRequest

Methods inherited from class java.lang.Object

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

Constructor Detail

BM25F

public BM25F()
      throws java.lang.Exception

Constructs an instance of the BM25F

Throws:

java.lang.Exception

Method Detail

getInfo

public java.lang.String getInfo()

Description copied from class: PerFieldNormWeightingModel

Returns the name of the model.

Specified by:

getInfo in interface Model

Overrides:

getInfo in class PerFieldNormWeightingModel

Returns:

java.lang.String