/*
* 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;
import org.apache.lucene.search.Explanation;
/**
* The probabilistic distribution used to model term occurrence
* in information-based models.
* @see IBSimilarity
* @lucene.experimental
*/
public abstract class Distribution {
/**
* Sole constructor. (For invocation by subclass
* constructors, typically implicit.)
*/
public Distribution() {}
/** Computes the score. */
public abstract float score(BasicStats stats, float tfn, float lambda);
/** Explains the score. Returns the name of the model only, since
* both {@code tfn} and {@code lambda} are explained elsewhere. */
public Explanation explain(BasicStats stats, float tfn, float lambda) {
return Explanation.match(
score(stats, tfn, lambda), getClass().getSimpleName());
}
/**
* Subclasses must override this method to return the name of the
* distribution.
*/
@Override
public abstract String toString();
}