org.apache.lucene.search.similarities

Class NormalizationZ

java.lang.Object

org.apache.lucene.search.similarities.Normalization

org.apache.lucene.search.similarities.NormalizationZ

public class NormalizationZ
extends Normalization

Pareto-Zipf Normalization

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

Constructors

Constructor and Description
NormalizationZ() Calls NormalizationZ(0.3)
NormalizationZ(float z) Creates NormalizationZ with the supplied parameter z.

Method Summary

Modifier and Type	Method and Description
float	getZ() Returns the parameter z
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

NormalizationZ

public NormalizationZ()

Calls NormalizationZ(0.3)

NormalizationZ

public NormalizationZ(float z)

Creates NormalizationZ with the supplied parameter z.

Parameters:

z - represents A/(A+1) where A measures the specificity of the language.

Method Detail

tfn

public 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

getZ

public float getZ()

Returns the parameter z

See Also:

NormalizationZ(float)