uk.ac.gla.terrier.matching.models.normalisation
Class NormalisationB

java.lang.Object
  uk.ac.gla.terrier.matching.models.normalisation.Normalisation
      uk.ac.gla.terrier.matching.models.normalisation.NormalisationB

All Implemented Interfaces:

java.io.Serializable

public class NormalisationB
extends Normalisation

This class implements BM25's normalisation method.

Version:

$Revision: 1.9 $

Author:

Ben He

See Also:

Serialized Form

Constructor Summary

NormalisationB()
The default constructor.

Method Summary

java.lang.String	getInfo() Get the name of the normalisation method.
double	normalise(double tf, double docLength, double termFrequency) This method gets the normalised term frequency.

Methods inherited from class uk.ac.gla.terrier.matching.models.normalisation.Normalisation

disableFieldRetrieval, enableFieldRetrieval, getFieldWeight, getParameter, setAverageDocumentLength, setDocumentFrequency, setFieldWeight, setNumberOfDocuments, setNumberOfTokens, setParameter

Methods inherited from class java.lang.Object

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

Constructor Detail

NormalisationB

public NormalisationB()

The default constructor. The hyper-parameter value is set to 0.75 by default.

Method Detail

getInfo

public java.lang.String getInfo()

Get the name of the normalisation method.

Specified by:

getInfo in class Normalisation

Returns:

Return the name of the normalisation method.

normalise

public double normalise(double tf,
                        double docLength,
                        double termFrequency)

This method gets the normalised term frequency.

Specified by:

normalise in class Normalisation

Parameters:

tf - The frequency of the query term in the document.

docLength - The number of tokens in the document.

termFrequency - The frequency of the query term in the collection.

Returns:

The normalised term frequency.