org.apache.lucene.search.similarities

Class DistributionSPL

java.lang.Object

org.apache.lucene.search.similarities.Distribution

org.apache.lucene.search.similarities.DistributionSPL

public class DistributionSPL
extends Distribution

The smoothed power-law (SPL) distribution for the information-based framework that is described in the original paper.

Unlike for DFR, the natural logarithm is used, as it is faster to compute and the original paper does not express any preference to a specific base.

WARNING: this model currently returns infinite scores for very small tf values and negative scores for very large tf values

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

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method and Description
double	score(BasicStats stats, double tfn, double lambda) Computes the score.
String	toString() Subclasses must override this method to return the name of the distribution.

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

explain

Methods inherited from class java.lang.Object

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

Constructor Detail

DistributionSPL

public DistributionSPL()

Sole constructor: parameter-free

Method Detail

score

public final double score(BasicStats stats,
                          double tfn,
                          double lambda)

Description copied from class: Distribution

Computes the score.

Specified by:

score in class Distribution

toString

public String toString()

Description copied from class: Distribution

Subclasses must override this method to return the name of the distribution.

Specified by:

toString in class Distribution