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source: branches/2925_AutoDiffForDynamicalModels/HeuristicLab.Encodings.RealVectorEncoding/3.3/Crossovers/LocalCrossover.cs

Last change on this file was 17246, checked in by gkronber, 5 years ago

#2925: merged r17037:17242 from trunk to branch

File size: 4.0 KB
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1#region License Information
2/* HeuristicLab
3 * Copyright (C) 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 HEAL.Attic;
26
27namespace HeuristicLab.Encodings.RealVectorEncoding {
28  /// <summary>
29  /// The local crossover for real vectors is similar to the <see cref="UniformAllPositionsArithmeticCrossover"/>, but where the factor alpha is chosen randomly in the interval [0;1) for each position.
30  /// </summary>
31  /// <remarks>
32  /// It is implemented as described in Dumitrescu, D. et al. (2000), Evolutionary computation, CRC Press, Boca Raton, FL, p. 194.
33  /// </remarks>
34  [Item("LocalCrossover", @"The local crossover is similar to the arithmetic all positions crossover, but uses a random alpha for each position x = alpha * p1 + (1-alpha) * p2. It is implemented as described in Dumitrescu, D. et al. (2000), Evolutionary computation, CRC Press, Boca Raton, FL., p. 194.")]
35  [StorableType("FB601681-7738-4380-889F-44A7CFA1D38F")]
36  public class LocalCrossover : RealVectorCrossover {
37    [StorableConstructor]
38    protected LocalCrossover(StorableConstructorFlag _) : base(_) { }
39    protected LocalCrossover(LocalCrossover original, Cloner cloner) : base(original, cloner) { }
40    public LocalCrossover() : base() { }
41
42    public override IDeepCloneable Clone(Cloner cloner) {
43      return new LocalCrossover(this, cloner);
44    }
45   
46    /// <summary>
47    /// Performs a local crossover on the two given parent vectors.
48    /// </summary>
49    /// <exception cref="ArgumentException">Thrown when two parents are not of the same length.</exception>
50    /// <param name="random">The random number generator.</param>
51    /// <param name="parent1">The first parent for the crossover operation.</param>
52    /// <param name="parent2">The second parent for the crossover operation.</param>
53    /// <returns>The newly created real vector, resulting from the local crossover.</returns>
54    public static RealVector Apply(IRandom random, RealVector parent1, RealVector parent2) {
55      if (parent1.Length != parent2.Length)
56        throw new ArgumentException("LocalCrossover: the two parents are not of the same length");
57
58      double factor;
59      int length = parent1.Length;
60      double[] result = new double[length];
61
62      for (int i = 0; i < length; i++) {
63        factor = random.NextDouble();
64        result[i] = (factor * parent1[i]) + ((1 - factor) * parent2[i]);
65      }
66      return new RealVector(result);
67    }
68
69    /// <summary>
70    /// Performs a local crossover operation for two given parent real vectors.
71    /// </summary>
72    /// <exception cref="ArgumentException">Thrown if there are not exactly two parents.</exception>
73    /// <param name="random">A random number generator.</param>
74    /// <param name="parents">An array containing the two real vectors that should be crossed.</param>
75    /// <returns>The newly created real vector, resulting from the crossover operation.</returns>
76    protected override RealVector Cross(IRandom random, ItemArray<RealVector> parents) {
77      if (parents.Length != 2) throw new ArgumentException("LocalCrossover: The number of parents is not equal to 2");
78      return Apply(random, parents[0], parents[1]);
79    }
80  }
81}
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