Class BasicModelD

  extended by
      extended by

public class BasicModelD
extends BasicModel

Implements the approximation of the binomial model with the divergence for DFR. The formula used in Lucene differs slightly from the one in the original paper: to avoid underflow for small values of N and F, N is increased by 1 and F is always increased by tfn+1.

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.

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

Constructor Summary
          Sole constructor: parameter-free
Method Summary
 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
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail


public BasicModelD()
Sole constructor: parameter-free

Method Detail


public final float score(BasicStats stats,
                         float tfn)
Description copied from class: BasicModel
Returns the informative content score.

Specified by:
score in class BasicModel


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

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