org.apache.lucene.search.similarities
Class BasicModel

java.lang.Object
  org.apache.lucene.search.similarities.BasicModel

Direct Known Subclasses:

BasicModelBE, BasicModelD, BasicModelG, BasicModelIF, BasicModelIn, BasicModelIne, BasicModelP

public abstract class BasicModel
extends Object

This class acts as the base class for the specific basic model implementations in the DFR framework. Basic models compute the informative content Inf₁ = -log₂Prob₁ .

See Also:

DFRSimilarity

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

Constructor Summary

BasicModel()
Sole constructor.

Method Summary

Explanation	explain(BasicStats stats, float tfn) Returns an explanation for the score.
abstract float	score(BasicStats stats, float tfn) Returns the informative content score.
abstract String	toString() Subclasses must override this method to return the code of the basic model formula.

Methods inherited from class java.lang.Object

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

Constructor Detail

BasicModel

public BasicModel()

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

Method Detail

score

public abstract float score(BasicStats stats,
                            float tfn)

Returns the informative content score.

explain

public Explanation explain(BasicStats stats,
                           float tfn)

Returns an explanation for the score.

Most basic models use the number of documents and the total term frequency to compute Inf₁. This method provides a generic explanation for such models. Subclasses that use other statistics must override this method.

toString

public abstract String toString()

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

Overrides:

toString in class Object