| /* |
| * 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 java.util.ArrayList; |
| import java.util.List; |
| |
| import org.apache.lucene.index.FieldInvertState; |
| import org.apache.lucene.search.CollectionStatistics; |
| import org.apache.lucene.search.Explanation; |
| import org.apache.lucene.search.TermStatistics; |
| |
| /** |
| * Implements the CombSUM method for combining evidence from multiple |
| * similarity values described in: Joseph A. Shaw, Edward A. Fox. |
| * In Text REtrieval Conference (1993), pp. 243-252 |
| * @lucene.experimental |
| */ |
| public class MultiSimilarity extends Similarity { |
| /** the sub-similarities used to create the combined score */ |
| protected final Similarity sims[]; |
| |
| /** Creates a MultiSimilarity which will sum the scores |
| * of the provided <code>sims</code>. */ |
| public MultiSimilarity(Similarity sims[]) { |
| this.sims = sims; |
| } |
| |
| @Override |
| public long computeNorm(FieldInvertState state) { |
| return sims[0].computeNorm(state); |
| } |
| |
| @Override |
| public SimScorer scorer(float boost, CollectionStatistics collectionStats, TermStatistics... termStats) { |
| SimScorer subScorers[] = new SimScorer[sims.length]; |
| for (int i = 0; i < subScorers.length; i++) { |
| subScorers[i] = sims[i].scorer(boost, collectionStats, termStats); |
| } |
| return new MultiSimScorer(subScorers); |
| } |
| |
| static class MultiSimScorer extends SimScorer { |
| private final SimScorer subScorers[]; |
| |
| MultiSimScorer(SimScorer subScorers[]) { |
| this.subScorers = subScorers; |
| } |
| |
| @Override |
| public float score(float freq, long norm) { |
| float sum = 0.0f; |
| for (SimScorer subScorer : subScorers) { |
| sum += subScorer.score(freq, norm); |
| } |
| return sum; |
| } |
| |
| @Override |
| public Explanation explain(Explanation freq, long norm) { |
| List<Explanation> subs = new ArrayList<>(); |
| for (SimScorer subScorer : subScorers) { |
| subs.add(subScorer.explain(freq, norm)); |
| } |
| return Explanation.match(score(freq.getValue().floatValue(), norm), "sum of:", subs); |
| } |
| |
| } |
| } |