org.apache.lucene.search.similarities.AfterEffect Maven / Gradle / Ivy
package org.apache.lucene.search.similarities;
/*
* 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.
*/
import org.apache.lucene.search.Explanation;
/**
* This class acts as the base class for the implementations of the first
* normalization of the informative content in the DFR framework. This
* component is also called the after effect and is defined by the
* formula Inf2 = 1 - Prob2, where
* Prob2 measures the information gain.
*
* @see DFRSimilarity
* @lucene.experimental
*/
public abstract class AfterEffect {
/**
* Sole constructor. (For invocation by subclass
* constructors, typically implicit.)
*/
public AfterEffect() {}
/** Returns the aftereffect score. */
public abstract float score(BasicStats stats, float tfn);
/** Returns an explanation for the score. */
public abstract Explanation explain(BasicStats stats, float tfn);
/** Implementation used when there is no aftereffect. */
public static final class NoAfterEffect extends AfterEffect {
/** Sole constructor: parameter-free */
public NoAfterEffect() {}
@Override
public final float score(BasicStats stats, float tfn) {
return 1f;
}
@Override
public final Explanation explain(BasicStats stats, float tfn) {
return Explanation.match(1, "no aftereffect");
}
@Override
public String toString() {
return "";
}
}
/**
* Subclasses must override this method to return the code of the
* after effect formula. Refer to the original paper for the list.
*/
@Override
public abstract String toString();
}