org.apache.lucene.search.similarities

Class AxiomaticF1EXP

java.lang.Object

org.apache.lucene.search.similarities.Similarity

org.apache.lucene.search.similarities.SimilarityBase

org.apache.lucene.search.similarities.Axiomatic

org.apache.lucene.search.similarities.AxiomaticF1EXP

public class AxiomaticF1EXP
extends Axiomatic

F1EXP is defined as Sum(tf(term_doc_freq)*ln(docLen)*IDF(term)) where IDF(t) = pow((N+1)/df(t), k) N=total num of docs, df=doc freq

WARNING: This API is experimental and might change in incompatible ways in the next release.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.search.similarities.Similarity

Similarity.SimScorer

Field Summary

Fields inherited from class org.apache.lucene.search.similarities.Axiomatic

k, queryLen, s

Fields inherited from class org.apache.lucene.search.similarities.SimilarityBase

discountOverlaps

Constructor Summary

Constructors

Constructor and Description
AxiomaticF1EXP() Default constructor
AxiomaticF1EXP(float s) Constructor setting s only, letting k and queryLen to default
AxiomaticF1EXP(float s, float k) Constructor setting s and k, letting queryLen to default

Method Summary

Modifier and Type	Method and Description
protected double	gamma(BasicStats stats, double freq, double docLen) compute the gamma component
protected double	idf(BasicStats stats, double freq, double docLen) compute the inverted document frequency component
protected Explanation	idfExplain(BasicStats stats, double freq, double docLen) Explain the score of the inverted document frequency component for a single document
protected double	ln(BasicStats stats, double freq, double docLen) compute the document length component
protected Explanation	lnExplain(BasicStats stats, double freq, double docLen) Explain the score of the document length component for a single document
protected double	tf(BasicStats stats, double freq, double docLen) compute the term frequency component
protected Explanation	tfExplain(BasicStats stats, double freq, double docLen) Explain the score of the term frequency component for a single document
protected double	tfln(BasicStats stats, double freq, double docLen) compute the mixed term frequency and document length component
protected Explanation	tflnExplain(BasicStats stats, double freq, double docLen) Explain the score of the mixed term frequency and document length component for a single document
String	toString() Name of the axiomatic method.

Methods inherited from class org.apache.lucene.search.similarities.Axiomatic

explain, explain, score

Methods inherited from class org.apache.lucene.search.similarities.SimilarityBase

computeNorm, fillBasicStats, getDiscountOverlaps, log2, newStats, scorer, setDiscountOverlaps

Methods inherited from class java.lang.Object

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

Constructor Detail

AxiomaticF1EXP

public AxiomaticF1EXP(float s,
                      float k)

Constructor setting s and k, letting queryLen to default

Parameters:

s - hyperparam for the growth function

k - hyperparam for the primitive weighting function

AxiomaticF1EXP

public AxiomaticF1EXP(float s)

Constructor setting s only, letting k and queryLen to default

Parameters:

s - hyperparam for the growth function

AxiomaticF1EXP

public AxiomaticF1EXP()

Default constructor

Method Detail

toString

public String toString()

Description copied from class: Axiomatic

Name of the axiomatic method.

Specified by:

toString in class Axiomatic

tf

protected double tf(BasicStats stats,
                    double freq,
                    double docLen)

compute the term frequency component

Specified by:

tf in class Axiomatic

ln

protected double ln(BasicStats stats,
                    double freq,
                    double docLen)

compute the document length component

Specified by:

ln in class Axiomatic

tfln

protected double tfln(BasicStats stats,
                      double freq,
                      double docLen)

compute the mixed term frequency and document length component

Specified by:

tfln in class Axiomatic

idf

protected double idf(BasicStats stats,
                     double freq,
                     double docLen)

compute the inverted document frequency component

Specified by:

idf in class Axiomatic

gamma

protected double gamma(BasicStats stats,
                       double freq,
                       double docLen)

compute the gamma component

Specified by:

gamma in class Axiomatic

tfExplain

protected Explanation tfExplain(BasicStats stats,
                                double freq,
                                double docLen)

Description copied from class: Axiomatic

Explain the score of the term frequency component for a single document

Specified by:

tfExplain in class Axiomatic

Parameters:

stats - the corpus level statistics

freq - number of occurrences of term in the document

docLen - the document length

Returns:

Explanation of how the tf component was computed

lnExplain

protected Explanation lnExplain(BasicStats stats,
                                double freq,
                                double docLen)

Description copied from class: Axiomatic

Explain the score of the document length component for a single document

Specified by:

lnExplain in class Axiomatic

Parameters:

stats - the corpus level statistics

freq - number of occurrences of term in the document

docLen - the document length

Returns:

Explanation of how the ln component was computed

tflnExplain

protected Explanation tflnExplain(BasicStats stats,
                                  double freq,
                                  double docLen)

Description copied from class: Axiomatic

Explain the score of the mixed term frequency and document length component for a single document

Specified by:

tflnExplain in class Axiomatic

Parameters:

stats - the corpus level statistics

freq - number of occurrences of term in the document

docLen - the document length

Returns:

Explanation of how the tfln component was computed

idfExplain

protected Explanation idfExplain(BasicStats stats,
                                 double freq,
                                 double docLen)

Description copied from class: Axiomatic

Explain the score of the inverted document frequency component for a single document

Specified by:

idfExplain in class Axiomatic

Parameters:

stats - the corpus level statistics

freq - number of occurrences of term in the document

docLen - the document length

Returns:

Explanation of how the idf component was computed