Package org.apache.lucene.search.similarities

Class AfterEffect

java.lang.Object

org.apache.lucene.search.similarities.AfterEffect

Direct Known Subclasses:

AfterEffectB, AfterEffectL

public abstract class AfterEffect
extends Object

This class acts as the base class for the implementations of the first normalization of the informative content in the DFR framework. This component is also called the after effect and is defined by the formula Inf₂ = 1 - Prob₂, where Prob₂ measures the information gain.

See Also:

• DFRSimilarity

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

Constructor Summary

Constructors

Constructor	Description
AfterEffect()	Sole constructor.

Method Summary

Modifier and Type	Method	Description
abstract Explanation	explain(BasicStats stats, double tfn)	Returns an explanation for the score.
abstract double	scoreTimes1pTfn(BasicStats stats)	Returns the product of the after effect with 1+tfn.
abstract String	toString()	Subclasses must override this method to return the code of the after effect formula.

Methods inherited from class java.lang.Object

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

Constructor Details

AfterEffect

public AfterEffect()

Sole constructor. (For invocation by subclass constructors, typically implicit.)

Method Details

scoreTimes1pTfn

public abstract double scoreTimes1pTfn(BasicStats stats)

Returns the product of the after effect with 1+tfn. This may not depend on the value of tfn.

explain

public abstract Explanation explain(BasicStats stats,
 double tfn)

Returns an explanation for the score.

toString

public abstract String toString()

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

Overrides:

toString in class Object