Package org.apache.lucene.search.similarities

Class BasicModelD

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

  • Constructor Details

    • BasicModelD

      public BasicModelD()
      Sole constructor: parameter-free

  • Method Details

    • 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