https://lucene.apache.org/lucene-parent/lucene-core: Apache Lucene Java Core (The Apache Software Foundation) 
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package org.apache.lucene.search.similarities;



Computes the measure of divergence from independence for DFI
scoring functions.


See http://trec.nist.gov/pubs/trec21/papers/irra.web.nb.pdf for more information
on different methods.

@lucene.experimental
/**
 * Computes the measure of divergence from independence for DFI
 * scoring functions.
 * <p>
 * See http://trec.nist.gov/pubs/trec21/papers/irra.web.nb.pdf for more information
 * on different methods.
 * @lucene.experimental
 */
public abstract class Independence {

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

/**
   * Sole constructor. (For invocation by subclass 
   * constructors, typically implicit.)
   */
  public Independence() {}
  
  
Computes distance from independence

Params:
  • freq – actual term frequency
  • expected – expected term frequency
/**
   * Computes distance from independence
   * @param freq actual term frequency
   * @param expected expected term frequency
   */
  public abstract double score(double freq, double expected);
  
  // subclasses must provide a name
  @Override
  public abstract String toString();
}