uk.ac.gla.terrier.matching.models
Class IFB2

java.lang.Object
  uk.ac.gla.terrier.matching.models.WeightingModel
      uk.ac.gla.terrier.matching.models.IFB2

All Implemented Interfaces:

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

public class IFB2
extends WeightingModel

This class implements the IFB2 weighting model.

Version:

$Revision: 1.19 $

Author:

Gianni Amati, Ben He, Vassilis Plachouras

See Also:

Serialized Form

Constructor Summary

IFB2()
A default constructor.

IFB2(double c)
Constructs an instance of this class with the specified value for the parameter c.

Method Summary

java.lang.String	getInfo() Returns the name of the model.
double	score(double tf, double docLength) Uses IFB2 to compute a weight for a term in a document.
double	score(double tf, double docLength, double n_t, double F_t, double keyFrequency) Uses IFB2 to compute a weight for a term in a document.

Methods inherited from class uk.ac.gla.terrier.matching.models.WeightingModel

clone, getParameter, setAverageDocumentLength, setDocumentFrequency, setKeyFrequency, setNumberOfDocuments, setNumberOfPointers, setNumberOfTokens, setNumberOfUniqueTerms, setParameter, setTermFrequency, stirlingPower

Methods inherited from class java.lang.Object

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

Constructor Detail

IFB2

public IFB2()

A default constructor. This must be followed by specifying the c value.

IFB2

public IFB2(double c)

Constructs an instance of this class with the specified value for the parameter c.

Parameters:

c - the term frequency normalisation parameter value.

Method Detail

getInfo

public final java.lang.String getInfo()

Returns the name of the model.

Specified by:

getInfo in interface Model

Specified by:

getInfo in class WeightingModel

Returns:

the name of the model

score

public final double score(double tf,
                          double docLength)

Uses IFB2 to compute a weight for a term in a document.

Specified by:

score in class WeightingModel

Parameters:

tf - The term frequency in the document

docLength - the document's length

Returns:

the score assigned to a document with the given tf and docLength, and other preset parameters

score

public final double score(double tf,
                          double docLength,
                          double n_t,
                          double F_t,
                          double keyFrequency)

Uses IFB2 to compute a weight for a term in a document.

Specified by:

score in class WeightingModel

Parameters:

tf - The term frequency in the document

docLength - the document's length

n_t - The document frequency of the term

F_t - the term frequency in the collection

keyFrequency - the term frequency in the query

Returns:

the score assigned by the weighting model IFB2.