| /* |
| * 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; |
| |
| /** |
| * This class acts as the base class for the specific <em>basic model</em> |
| * implementations in the DFR framework. Basic models compute the |
| * <em>informative content Inf<sub>1</sub> = -log<sub>2</sub>Prob<sub>1</sub> |
| * </em>. |
| * |
| * @see DFRSimilarity |
| * @lucene.experimental |
| */ |
| public abstract class BasicModel { |
| |
| /** |
| * Sole constructor. (For invocation by subclass |
| * constructors, typically implicit.) |
| */ |
| public BasicModel() {} |
| |
| /** Returns the informative content score combined with the after effect, more specifically |
| * {@code informationContentScore * aeTimes1pTfn / (1 + tfn)}. This function must be |
| * non-decreasing with {@code tfn}. */ |
| public abstract double score(BasicStats stats, double tfn, double aeTimes1pTfn); |
| |
| |
| /** |
| * Returns an explanation for the score. |
| * Subclasses must override this method. |
| */ |
| public abstract Explanation explain (BasicStats stats, double tfn, double aeTimes1pTfn); |
| |
| /** |
| * Subclasses must override this method to return the code of the |
| * basic model formula. Refer to the original paper for the list. |
| */ |
| @Override |
| public abstract String toString(); |
| } |