org.apache.lucene.search.similarities
Class BasicModelP

java.lang.Object
  extended by org.apache.lucene.search.similarities.BasicModel
      extended by org.apache.lucene.search.similarities.BasicModelP

public class BasicModelP
extends BasicModel

Implements the Poisson approximation for the binomial model for DFR.

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

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.


Field Summary
protected static double LOG2_E
          log2(Math.E), precomputed.
 
Constructor Summary
BasicModelP()
          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 org.apache.lucene.search.similarities.BasicModel
explain
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

LOG2_E

protected static double LOG2_E
log2(Math.E), precomputed.

Constructor Detail

BasicModelP

public BasicModelP()
Sole constructor: parameter-free

Method Detail

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


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