org.terrier.matching.models

Class Dl

java.lang.Object

org.terrier.matching.models.WeightingModel

org.terrier.matching.models.Dl

All Implemented Interfaces:

Serializable, Cloneable, Model

public class Dl
extends WeightingModel

This class implements a simple document length weighting model.

Since:

4.0

Author:

Craig Macdonald

See Also:

Serialized Form

Field Summary

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

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

Constructor Summary

Constructors

Constructor and Description
Dl()
Dl(double b)

Method Summary

Methods

Modifier and Type	Method and Description
String	getInfo() Returns the name of the model.
double	getParameter() Returns the b parameter to the ranking formula as set by setParameter()
double	score(double tf, double docLength) This method provides the contract for implementing weighting models.
double	score(double tf, double docLength, double documentFrequency, double termFrequency, double keyFrequency) This method provides the contract for implementing weighting models.
void	setParameter(double b) Sets the b parameter to ranking formula

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

clone, getOverflowed, prepare, score, setCollectionStatistics, setEntryStatistics, setKeyFrequency, setRequest

Methods inherited from class java.lang.Object

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

Constructor Detail

Dl

public Dl()

Dl

public Dl(double b)

Method Detail

getInfo

public final String getInfo()

Description copied from class: WeightingModel

Returns the name of the model.

Specified by:

getInfo in interface Model

Specified by:

getInfo in class WeightingModel

Returns:

java.lang.String

score

public final double score(double tf,
           double docLength)

Description copied from class: WeightingModel

This method provides the contract for implementing weighting models.

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 documentFrequency,
           double termFrequency,
           double keyFrequency)

Description copied from class: WeightingModel

This method provides the contract for implementing weighting models. As of Terrier 3.6, the 5-parameter score method is being deprecated since is is not used. The two parameter score method should be used instead. Tagged for removal in a later version.

Specified by:

score in class WeightingModel

Parameters:

tf - The term frequency in the document

docLength - the document's length

documentFrequency - The document frequency of the term

termFrequency - the term frequency in the collection

keyFrequency - the term frequency in the query

Returns:

the score returned by the implemented weighting model.

setParameter

public void setParameter(double b)

Sets the b parameter to ranking formula

Specified by:

setParameter in interface Model

Overrides:

setParameter in class WeightingModel

Parameters:

b - the b parameter value to use.

getParameter

public double getParameter()

Returns the b parameter to the ranking formula as set by setParameter()

Specified by:

getParameter in interface Model

Overrides:

getParameter in class WeightingModel