org.terrier.matching.tsms

Class TermInFieldModifier

java.lang.Object

org.terrier.matching.models.WeightingModel

org.terrier.matching.tsms.TermInFieldModifier

All Implemented Interfaces:

Serializable, Cloneable, Model, IndexConfigurable

public class TermInFieldModifier
extends WeightingModel
implements IndexConfigurable

Resets the scores of documents according to whether a term appears in a given set of fields. This class implements the TermScoreModifier interface.

Author:

Vassilis Plachouras

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected String	field The fields that a query term should appear in.
protected Index	index
protected boolean	requirement The requirement.

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
TermInFieldModifier(String _field) Constructs an instance of a TermInFieldModifier given a field that the corresponding query term should appear in.
TermInFieldModifier(String _field, boolean req) Constructs an instance of a TermInFieldModifier given a field that the corresponding query term should appear in.

Method Summary

Methods

Modifier and Type	Method and Description
String	getInfo() Returns the name of the model.
String	getName() Returns the name of the class and whether the query term is required.
int	modifyScores(double[] scores, int[][] pointers) Resets the scores of documents for a particular term, based on the fields a term appears in documents.
void	prepare() prepare
double	score(double tf, double docLength) This method provides the contract for implementing weighting models.
double	score(double tf, double docLength, double n_t, double F_t, double _keyFrequency) Deprecated.
double	score(Posting _p) Returns score
void	setIndex(Index i) Tell the implementer which Index object it is associated with.

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

clone, getOverflowed, getParameter, setCollectionStatistics, setEntryStatistics, setKeyFrequency, setParameter, setRequest

Methods inherited from class java.lang.Object

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

Field Detail

index

protected transient Index index

field

protected String field

The fields that a query term should appear in.

requirement

protected boolean requirement

The requirement. By default it is true.

Constructor Detail

TermInFieldModifier

public TermInFieldModifier(String _field)

Constructs an instance of a TermInFieldModifier given a field that the corresponding query term should appear in.

Parameters:

_field - String a field

TermInFieldModifier

public TermInFieldModifier(String _field,
                   boolean req)

Constructs an instance of a TermInFieldModifier given a field that the corresponding query term should appear in.

Parameters:

_field - String a field

req - boolean the requirement for this field. If req is true, then the term is required to appear in the field (this is the default behaviour), otherwise the term should not appear in the field.

Method Detail

modifyScores

public int modifyScores(double[] scores,
               int[][] pointers)

Resets the scores of documents for a particular term, based on the fields a term appears in documents.

Parameters:

scores - double[] the scores of the documents.

pointers - int[][] the pointers read from the inverted file for a particular query term.

Returns:

the number of documents for which the scores were modified.

prepare

public void prepare()

prepare

Overrides:

prepare in class WeightingModel

score

public double score(Posting _p)

Returns score

Overrides:

score in class WeightingModel

Returns:

score

getName

public String getName()

Returns the name of the class and whether the query term is required.

getInfo

public 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 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

setIndex

public void setIndex(Index i)

Tell the implementer which Index object it is associated with.

Specified by:

setIndex in interface IndexConfigurable

Parameters:

i - Index object to use

score

@Deprecated
public double score(double tf,
                      double docLength,
                      double n_t,
                      double F_t,
                      double _keyFrequency)

Deprecated.

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

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 returned by the implemented weighting model.