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

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

All Implemented Interfaces:

java.io.Serializable, Model

public class DFRWeightingModel
extends WeightingModel

This class implements a modular DFR model. Components in the model are specified individually. Besides of the basic model, the other two components can be either specified or disabled.

Version:

$Revision: 1.20 $

Author:

Ben He

See Also:

Serialized Form

Constructor Summary

DFRWeightingModel(java.lang.String[] components)
The default constructor.

Method Summary

java.lang.String	getInfo() Returns the name of the model.
double	getParameter() Return the parameter set by setParameter()
double	score(double tf, double docLength) Compute a weight for a term in a document.
double	score(double tf, double docLength, double documentFrequency, double termFrequency, double queryTermWeight) Compute a weight for a term in a document.
void	setAverageDocumentLength(double avgDocLength) Sets the average length of documents in the collection.
void	setDocumentFrequency(double docFreq) Sets the document frequency of the term in the collection.
void	setNumberOfDocuments(double numOfDocs) Sets the number of documents in the collection.
void	setNumberOfTokens(double value) Set the number of tokens in the collection.
void	setNumberOfUniqueTerms(double number) Set the number of unique terms in the collection.
void	setParameter(double value) Set the frequency normalisation parameter.

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

setKeyFrequency, setNumberOfPointers, setTermFrequency, stirlingPower

Methods inherited from class java.lang.Object

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

Constructor Detail

DFRWeightingModel

public DFRWeightingModel(java.lang.String[] components)

The default constructor. Takes an array of strings to define the Basic Model, the After Effect component and the Normalisation component. If the array is less than 3 items in length, then empty strings will be passed instead of the After Effect and/or Normalisation components.

Parameters:

components - Corresponds to the names of the 3 DFR weighting models component names, as passed to initialise().

Method Detail

setAverageDocumentLength

public void setAverageDocumentLength(double avgDocLength)

Sets the average length of documents in the collection.

Specified by:

setAverageDocumentLength in interface Model

Overrides:

setAverageDocumentLength in class WeightingModel

Parameters:

avgDocLength - The documents' average length.

setNumberOfDocuments

public void setNumberOfDocuments(double numOfDocs)

Sets the number of documents in the collection.

Specified by:

setNumberOfDocuments in interface Model

Overrides:

setNumberOfDocuments in class WeightingModel

Parameters:

numOfDocs - the number of documents in the collection.

setNumberOfTokens

public void setNumberOfTokens(double value)

Set the number of tokens in the collection.

Specified by:

setNumberOfTokens in interface Model

Overrides:

setNumberOfTokens in class WeightingModel

Parameters:

value - The number of tokens in the collection.

setNumberOfUniqueTerms

public void setNumberOfUniqueTerms(double number)

Set the number of unique terms in the collection.

Specified by:

setNumberOfUniqueTerms in interface Model

Overrides:

setNumberOfUniqueTerms in class WeightingModel

Parameters:

number - double The number of unique terms in the collection.

setParameter

public void setParameter(double value)

Set the frequency normalisation parameter.

Specified by:

setParameter in interface Model

Overrides:

setParameter in class WeightingModel

Parameters:

value - The given parameter value.

getParameter

public double getParameter()

Return the parameter set by setParameter()

Specified by:

getParameter in interface Model

Overrides:

getParameter in class WeightingModel

Returns:

parameter double value

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.

setDocumentFrequency

public void setDocumentFrequency(double docFreq)

Sets the document frequency of the term in the collection.

Overrides:

setDocumentFrequency in class WeightingModel

Parameters:

docFreq - the document frequency of the term in the collection.

score

public final double score(double tf,
                          double docLength)

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 documentFrequency,
                          double termFrequency,
                          double queryTermWeight)

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

documentFrequency - The document frequency of the term

termFrequency - the term frequency in the collection

queryTermWeight - the term frequency in the query

Returns:

the score assigned by the weighting model PL2.