| 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 implementations of the <em>first |
| /// normalization of the informative content</em> in the DFR framework. This |
| /// component is also called the <em>after effect</em> and is defined by the |
| /// formula <em>Inf<sub>2</sub> = 1 - Prob<sub>2</sub></em>, where |
| /// <em>Prob<sub>2</sub></em> measures the <em>information gain</em>. |
| /// <para/> |
| /// @lucene.experimental |
| /// </summary> |
| /// <seealso cref="DFRSimilarity"/> |
| public abstract class AfterEffect |
| { |
| /// <summary> |
| /// Sole constructor. (For invocation by subclass |
| /// constructors, typically implicit.) |
| /// </summary> |
| public AfterEffect() |
| { |
| } |
| |
| /// <summary> |
| /// Returns the aftereffect score. </summary> |
| public abstract float Score(BasicStats stats, float tfn); |
| |
| /// <summary> |
| /// Returns an explanation for the score. </summary> |
| public abstract Explanation Explain(BasicStats stats, float tfn); |
| |
| /// <summary> |
| /// Implementation used when there is no aftereffect. </summary> |
| public sealed class NoAfterEffect : AfterEffect |
| { |
| /// <summary> |
| /// Sole constructor: parameter-free </summary> |
| public NoAfterEffect() |
| { |
| } |
| |
| public override float Score(BasicStats stats, float tfn) |
| { |
| return 1f; |
| } |
| |
| public override Explanation Explain(BasicStats stats, float tfn) |
| { |
| return new Explanation(1, "no aftereffect"); |
| } |
| |
| public override string ToString() |
| { |
| return ""; |
| } |
| } |
| |
| /// <summary> |
| /// Subclasses must override this method to return the code of the |
| /// after effect formula. Refer to the original paper for the list. |
| /// </summary> |
| public override abstract string ToString(); |
| } |
| } |