| 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 java.io.IOException; |
| |
| import org.apache.lucene.index.AtomicReaderContext; |
| import org.apache.lucene.index.FieldInvertState; |
| import org.apache.lucene.search.CollectionStatistics; |
| import org.apache.lucene.search.Explanation; |
| import org.apache.lucene.search.TermStatistics; |
| import org.apache.lucene.util.BytesRef; |
| |
| /** |
| * 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 SimWeight computeWeight(float queryBoost, CollectionStatistics collectionStats, TermStatistics... termStats) { |
| SimWeight subStats[] = new SimWeight[sims.length]; |
| for (int i = 0; i < subStats.length; i++) { |
| subStats[i] = sims[i].computeWeight(queryBoost, collectionStats, termStats); |
| } |
| return new MultiStats(subStats); |
| } |
| |
| @Override |
| public SimScorer simScorer(SimWeight stats, AtomicReaderContext context) throws IOException { |
| SimScorer subScorers[] = new SimScorer[sims.length]; |
| for (int i = 0; i < subScorers.length; i++) { |
| subScorers[i] = sims[i].simScorer(((MultiStats)stats).subStats[i], context); |
| } |
| return new MultiSimScorer(subScorers); |
| } |
| |
| static class MultiSimScorer extends SimScorer { |
| private final SimScorer subScorers[]; |
| |
| MultiSimScorer(SimScorer subScorers[]) { |
| this.subScorers = subScorers; |
| } |
| |
| @Override |
| public float score(int doc, float freq) { |
| float sum = 0.0f; |
| for (SimScorer subScorer : subScorers) { |
| sum += subScorer.score(doc, freq); |
| } |
| return sum; |
| } |
| |
| @Override |
| public Explanation explain(int doc, Explanation freq) { |
| Explanation expl = new Explanation(score(doc, freq.getValue()), "sum of:"); |
| for (SimScorer subScorer : subScorers) { |
| expl.addDetail(subScorer.explain(doc, freq)); |
| } |
| return expl; |
| } |
| |
| @Override |
| public float computeSlopFactor(int distance) { |
| return subScorers[0].computeSlopFactor(distance); |
| } |
| |
| @Override |
| public float computePayloadFactor(int doc, int start, int end, BytesRef payload) { |
| return subScorers[0].computePayloadFactor(doc, start, end, payload); |
| } |
| } |
| |
| static class MultiStats extends SimWeight { |
| final SimWeight subStats[]; |
| |
| MultiStats(SimWeight subStats[]) { |
| this.subStats = subStats; |
| } |
| |
| @Override |
| public float getValueForNormalization() { |
| float sum = 0.0f; |
| for (SimWeight stat : subStats) { |
| sum += stat.getValueForNormalization(); |
| } |
| return sum / subStats.length; |
| } |
| |
| @Override |
| public void normalize(float queryNorm, float topLevelBoost) { |
| for (SimWeight stat : subStats) { |
| stat.normalize(queryNorm, topLevelBoost); |
| } |
| } |
| } |
| } |