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source: branches/gteufl/HeuristicLab.Encodings.RealVectorEncoding/3.3/Crossovers/DiscreteCrossover.cs @ 12969

Last change on this file since 12969 was 12969, checked in by gkronber, 9 years ago

#2478 merged all changes from trunk to branch before trunk-reintegration

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1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2015 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
4 *
5 * This file is part of HeuristicLab.
6 *
7 * HeuristicLab is free software: you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation, either version 3 of the License, or
10 * (at your option) any later version.
11 *
12 * HeuristicLab is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
19 */
20#endregion
21
22using System;
23using HeuristicLab.Common;
24using HeuristicLab.Core;
25using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
26
27namespace HeuristicLab.Encodings.RealVectorEncoding {
28  /// <summary>
29  /// Discrete crossover for real vectors: For each position in the new vector an allele
30  /// of one of the parents is randomly selected.
31  /// </summary>
32  /// <remarks>
33  /// This operator is also called dominant recombination and unlike other crossovers works on more than two parents also.<br />
34  /// It is implemented as described in Beyer, H.-G. and Schwefel, H.-P. 2002. Evolution Strategies - A Comprehensive Introduction Natural Computing, 1, pp. 3-52.
35  /// </remarks>
36  [Item("DiscreteCrossover", "Discrete crossover for real vectors: Creates a new offspring by combining the alleles in the parents such that each allele is randomly selected from one parent. It is implemented as described in Beyer, H.-G. and Schwefel, H.-P. 2002. Evolution Strategies - A Comprehensive Introduction Natural Computing, 1, pp. 3-52.")]
37  [StorableClass]
38  public class DiscreteCrossover : RealVectorCrossover {
39    [StorableConstructor]
40    protected DiscreteCrossover(bool deserializing) : base(deserializing) { }
41    protected DiscreteCrossover(DiscreteCrossover original, Cloner cloner) : base(original, cloner) { }
42    public DiscreteCrossover() : base() { }
43
44    public override IDeepCloneable Clone(Cloner cloner) {
45      return new DiscreteCrossover(this, cloner);
46    }
47   
48    /// <summary>
49    /// Performs a discrete crossover operation on multiple parents.
50    /// </summary>
51    /// <exception cref="ArgumentException">Thrown when the vectors of the parents are of different length.</exception>
52    /// <param name="random">A random number generator.</param>
53    /// <param name="parents">An array containing the parents that should be crossed.</param>
54    /// <returns>The newly created real vector, resulting from the crossover operation.</returns>
55    public static RealVector Apply(IRandom random, ItemArray<RealVector> parents) {
56      int length = parents[0].Length;
57
58      for (int i = 0; i < parents.Length; i++) {
59        if (parents[i].Length != length)
60          throw new ArgumentException("DiscreteCrossover: The parents' vectors are of different length.", "parents");
61      }
62
63      RealVector result = new RealVector(length);
64      for (int i = 0; i < length; i++) {
65        result[i] = parents[random.Next(parents.Length)][i];
66      }
67
68      return result;
69    }
70
71    /// <summary>
72    /// Checks number of parents and forwards the call to <see cref="Apply(IRandom, ItemArray<RealVector>)"/>.
73    /// </summary>
74    /// <exception cref="ArgumentException">Thrown when <paramref name="parents"/> contains less than 2 elements.</exception>
75    /// <param name="random">The random number generator.</param>
76    /// <param name="parents">The collection of parents (must be of size 2 or greater).</param>
77    /// <returns>The real vector resulting from the crossover.</returns>
78    protected override RealVector Cross(IRandom random, ItemArray<RealVector> parents) {
79      if (parents.Length < 2) throw new ArgumentException("DiscreteCrossover: The number of parents is less than 2.", "parents");
80      return Apply(random, parents);
81    }
82  }
83}
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