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Diffstat (limited to 'src/core/Search/Function/CustomScoreProvider.cs')
| -rw-r--r-- | src/core/Search/Function/CustomScoreProvider.cs | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/src/core/Search/Function/CustomScoreProvider.cs b/src/core/Search/Function/CustomScoreProvider.cs new file mode 100644 index 0000000..630edf4 --- /dev/null +++ b/src/core/Search/Function/CustomScoreProvider.cs @@ -0,0 +1,175 @@ +/* + * 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. + */ + +using System; +using System.Collections.Generic; +using System.Text; + +using Lucene.Net.Index; + +namespace Lucene.Net.Search.Function +{ + /// <summary> + /// An instance of this subclass should be returned by + /// <see cref="CustomScoreQuery.GetCustomScoreProvider" />, if you want + /// to modify the custom score calculation of a <see cref="CustomScoreQuery" />. + /// <para>Since Lucene 2.9, queries operate on each segment of an Index separately, + /// so overriding the similar (now deprecated) methods in <see cref="CustomScoreQuery" /> + /// is no longer suitable, as the supplied <c>doc</c> ID is per-segment + /// and without knowledge of the IndexReader you cannot access the + /// document or <see cref="FieldCache" />.</para> + /// + /// @lucene.experimental + /// @since 2.9.2 + /// </summary> + public class CustomScoreProvider + { + + protected IndexReader reader; + + /// <summary> + /// Creates a new instance of the provider class for the given IndexReader. + /// </summary> + public CustomScoreProvider(IndexReader reader) + { + this.reader = reader; + } + + /// <summary> + /// * Compute a custom score by the subQuery score and a number of + /// ValueSourceQuery scores. + /// <p/> + /// Subclasses can override this method to modify the custom score. + /// <p/> + /// If your custom scoring is different than the default herein you + /// should override at least one of the two customScore() methods. + /// If the number of ValueSourceQueries is always < 2 it is + /// sufficient to override the other + /// <see cref="CustomScore(int, float, float)">CustomScore()</see> + /// method, which is simpler. + /// <p/> + /// The default computation herein is a multiplication of given scores: + /// <pre> + /// ModifiedScore = valSrcScore * valSrcScores[0] * valSrcScores[1] * ... + /// </pre> + /// </summary> + /// <param name="doc">id of scored doc</param> + /// <param name="subQueryScore">score of that doc by the subQuery</param> + /// <param name="valSrcScores">scores of that doc by the ValueSourceQuery</param> + /// <returns>custom score</returns> + public virtual float CustomScore(int doc, float subQueryScore, float[] valSrcScores) + { + if (valSrcScores.Length == 1) + { + return CustomScore(doc, subQueryScore, valSrcScores[0]); + } + if (valSrcScores.Length == 0) + { + return CustomScore(doc, subQueryScore, 1); + } + float score = subQueryScore; + for (int i = 0; i < valSrcScores.Length; i++) + { + score *= valSrcScores[i]; + } + return score; + } + + /// <summary> + /// Compute a custom score by the subQuery score and the ValueSourceQuery score. + /// <p/> + /// Subclasses can override this method to modify the custom score. + /// <p/> + /// If your custom scoring is different than the default herein you + /// should override at least one of the two customScore() methods. + /// If the number of ValueSourceQueries is always < 2 it is + /// sufficient to override this customScore() method, which is simpler. + /// <p/> + /// The default computation herein is a multiplication of the two scores: + /// <pre> + /// ModifiedScore = subQueryScore * valSrcScore + /// </pre> + /// </summary> + /// <param name="doc">id of scored doc</param> + /// <param name="subQueryScore">score of that doc by the subQuery</param> + /// <param name="valSrcScore">score of that doc by the ValueSourceQuery</param> + /// <returns>custom score</returns> + public virtual float CustomScore(int doc, float subQueryScore, float valSrcScore) + { + return subQueryScore * valSrcScore; + } + + /// <summary> + /// Explain the custom score. + /// Whenever overriding <see cref="CustomScore(int, float, float[])" />, + /// this method should also be overridden to provide the correct explanation + /// for the part of the custom scoring. + /// </summary> + /// <param name="doc">doc being explained</param> + /// <param name="subQueryExpl">explanation for the sub-query part</param> + /// <param name="valSrcExpls">explanation for the value source part</param> + /// <returns>an explanation for the custom score</returns> + public virtual Explanation CustomExplain(int doc, Explanation subQueryExpl, Explanation[] valSrcExpls) + { + if (valSrcExpls.Length == 1) + { + return CustomExplain(doc, subQueryExpl, valSrcExpls[0]); + } + if (valSrcExpls.Length == 0) + { + return subQueryExpl; + } + float valSrcScore = 1; + for (int i = 0; i < valSrcExpls.Length; i++) + { + valSrcScore *= valSrcExpls[i].Value; + } + Explanation exp = new Explanation(valSrcScore * subQueryExpl.Value, "custom score: product of:"); + exp.AddDetail(subQueryExpl); + for (int i = 0; i < valSrcExpls.Length; i++) + { + exp.AddDetail(valSrcExpls[i]); + } + return exp; + } + + /// <summary> + /// Explain the custom score. + /// Whenever overriding <see cref="CustomScore(int, float, float)" />, + /// this method should also be overridden to provide the correct explanation + /// for the part of the custom scoring. + /// + /// </summary> + /// <param name="doc">doc being explained</param> + /// <param name="subQueryExpl">explanation for the sub-query part</param> + /// <param name="valSrcExpl">explanation for the value source part</param> + /// <returns>an explanation for the custom score</returns> + public virtual Explanation CustomExplain(int doc, Explanation subQueryExpl, Explanation valSrcExpl) + { + float valSrcScore = 1; + if (valSrcExpl != null) + { + valSrcScore *= valSrcExpl.Value; + } + Explanation exp = new Explanation(valSrcScore * subQueryExpl.Value, "custom score: product of:"); + exp.AddDetail(subQueryExpl); + exp.AddDetail(valSrcExpl); + return exp; + } + + } +} |