/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.lucene.search.similarities;
/**
* 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.)
*/
public Independence() {}
/**
* Computes distance from independence
* @param freq actual term frequency
* @param expected expected term frequency
*/
public abstract float score(float freq, float expected);
// subclasses must provide a name
@Override
public abstract String toString();
}