org.apache.lucene.search.similarities
Class NormalizationH1

java.lang.Object
  org.apache.lucene.search.similarities.Normalization
      org.apache.lucene.search.similarities.NormalizationH1

public class NormalizationH1
extends Normalization

Normalization model that assumes a uniform distribution of the term frequency.

While this model is parameterless in the original article, information-based models (see IBSimilarity) introduced a multiplying factor. The default value for the c parameter is 1.

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.Normalization

Normalization.NoNormalization

Constructor Summary

NormalizationH1()
Calls NormalizationH1(1)

NormalizationH1(float c)
Creates NormalizationH1 with the supplied parameter c.

Method Summary

float	getC() Returns the c parameter.
float	tfn(BasicStats stats, float tf, float len) Returns the normalized term frequency.
String	toString() Subclasses must override this method to return the code of the normalization formula.

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

explain

Methods inherited from class java.lang.Object

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

Constructor Detail

NormalizationH1

public NormalizationH1(float c)

Creates NormalizationH1 with the supplied parameter c.

Parameters:

c - hyper-parameter that controls the term frequency normalization with respect to the document length.

NormalizationH1

public NormalizationH1()

Calls NormalizationH1(1)

Method Detail

tfn

public final float tfn(BasicStats stats,
                       float tf,
                       float len)

Description copied from class: Normalization

Returns the normalized term frequency.

Specified by:

tfn in class Normalization

len - the field length.

toString

public String toString()

Description copied from class: Normalization

Subclasses must override this method to return the code of the normalization formula. Refer to the original paper for the list.

Specified by:

toString in class Normalization

getC

public float getC()

Returns the c parameter.

See Also:

NormalizationH1(float)