org.apache.lucene.search.similarities

Class BasicModelP

java.lang.Object

org.apache.lucene.search.similarities.BasicModel

org.apache.lucene.search.similarities.BasicModelP

public class BasicModelP
extends BasicModel

Implements the Poisson approximation for the binomial model for DFR.

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

WARNING: for terms that do not meet the expected random distribution (e.g. stopwords), this model may give poor performance, such as abnormally high scores for low tf values.

Field Summary

Fields

Modifier and Type	Field and Description
protected static double	LOG2_E log2(Math.E), precomputed.

Constructor Summary

Constructors

Constructor and Description
BasicModelP() Sole constructor: parameter-free

Method Summary

Methods

Modifier and Type	Method and Description
float	score(BasicStats stats, float tfn) Returns the informative content score.
String	toString() Subclasses must override this method to return the code of the basic model formula.

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

explain

Methods inherited from class java.lang.Object

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

Field Detail

LOG2_E

protected static double LOG2_E

log2(Math.E), precomputed.

Constructor Detail

BasicModelP

public BasicModelP()

Sole constructor: parameter-free

Method Detail

score

public final float score(BasicStats stats,
          float tfn)

Description copied from class: BasicModel

Returns the informative content score.

Specified by:

score in class BasicModel

toString

public String toString()

Description copied from class: BasicModel

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

Specified by:

toString in class BasicModel