org.terrier.matching.models
Class DLH

java.lang.Object
  extended by org.terrier.matching.models.WeightingModel
      extended by org.terrier.matching.models.DLH
All Implemented Interfaces:
java.io.Serializable, java.lang.Cloneable, Model

public class DLH
extends WeightingModel

This class implements the DLH weighting model. This is a parameter-free weighting model. Even if the user specifies a parameter value, it will NOT affect the results. It is highly recomended to use the model with query expansion.

References

  1. Frequentist and Bayesian approach to Information Retrieval. G. Amati. In Proceedings of the 28th European Conference on IR Research (ECIR 2006). LNCS vol 3936, pages 13--24.

Author:
Gianni Amati, Ben He, Vassilis Plachouras
See Also:
Serialized Form

Field Summary
 
Fields inherited from class org.terrier.matching.models.WeightingModel
averageDocumentLength, c, documentFrequency, i, keyFrequency, numberOfDocuments, numberOfPointers, numberOfTokens, numberOfUniqueTerms, termFrequency
 
Constructor Summary
DLH()
          A default constructor.
 
Method Summary
 java.lang.String getInfo()
          Returns the name of the model.
 double score(double tf, double docLength)
          Uses DLH 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 DLH to compute a weight for a term in a document.
 
Methods inherited from class org.terrier.matching.models.WeightingModel
clone, getOverflowed, getParameter, prepare, score, setAverageDocumentLength, setCollectionStatistics, setDocumentFrequency, setEntryStatistics, setKeyFrequency, setNumberOfDocuments, setNumberOfPointers, setNumberOfTokens, setNumberOfUniqueTerms, setParameter, setRequest, setTermFrequency, stirlingPower
 
Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

DLH

public DLH()
A default constructor.

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 DLH 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 DLH 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 DLH.


Terrier 3.5. Copyright © 2004-2011 University of Glasgow