| namespace Lucene.Net.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. |
| */ |
| |
| /// <summary> |
| /// 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>. |
| /// <para/> |
| /// @lucene.experimental |
| /// </summary> |
| /// <seealso cref="DFRSimilarity"/> |
| public abstract class BasicModel |
| { |
| /// <summary> |
| /// Sole constructor. (For invocation by subclass |
| /// constructors, typically implicit.) |
| /// </summary> |
| protected BasicModel() // LUCENENET: CA1012: Abstract types should not have constructors (marked protected) |
| { |
| } |
| |
| /// <summary> |
| /// Returns the informative content score. </summary> |
| public abstract float Score(BasicStats stats, float tfn); |
| |
| /// <summary> |
| /// Returns an explanation for the score. |
| /// <para>Most basic models use the number of documents and the total term |
| /// frequency to compute Inf<sub>1</sub>. this method provides a generic |
| /// explanation for such models. Subclasses that use other statistics must |
| /// override this method.</para> |
| /// </summary> |
| public virtual Explanation Explain(BasicStats stats, float tfn) |
| { |
| Explanation result = new Explanation(); |
| result.Description = this.GetType().Name + ", computed from: "; |
| result.Value = Score(stats, tfn); |
| result.AddDetail(new Explanation(tfn, "tfn")); |
| result.AddDetail(new Explanation(stats.NumberOfDocuments, "numberOfDocuments")); |
| result.AddDetail(new Explanation(stats.TotalTermFreq, "totalTermFreq")); |
| return result; |
| } |
| |
| /// <summary> |
| /// Subclasses must override this method to return the code of the |
| /// basic model formula. Refer to the original paper for the list. |
| /// </summary> |
| public override abstract string ToString(); |
| } |
| } |