source: branches/2994-AutoDiffForIntervals/HeuristicLab.Encodings.PermutationEncoding/3.3/Crossovers/CosaCrossover.cs @ 17209

Last change on this file since 17209 was 17209, checked in by gkronber, 5 weeks ago

#2994: merged r17132:17198 from trunk to branch

File size: 6.0 KB
Line 
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.PermutationEncoding {
28  /// <summary>
29  /// Performs the crossover described in the COSA optimization method.
30  /// </summary>
31  /// <remarks>
32  /// It is implemented as described in Wendt, O. 1994. COSA: COoperative Simulated Annealing - Integration von Genetischen Algorithmen und Simulated Annealing am Beispiel der Tourenplanung. Dissertation Thesis. IWI Frankfurt.<br />
33  /// The operator actually performs a 2-opt mutation on the first parent, but it uses the second parent to determine which new edge should be inserted.
34  /// Thus the mutation is not random as the second breakpoint depends on the information that is encoded in other members of the population.
35  /// The idea is that the child should not sit right inbetween the two parents, but rather go a little bit from one parent in direction to the other.
36  /// </remarks>
37  [Item("CosaCrossover", "An operator which performs the crossover described in the COSA optimization method. It is implemented as described in Wendt, O. 1994. COSA: COoperative Simulated Annealing - Integration von Genetischen Algorithmen und Simulated Annealing am Beispiel der Tourenplanung. Dissertation Thesis. IWI Frankfurt.")]
38  [StorableType("2C6B5F27-A921-4CDD-A484-35B8824CDDBE")]
39  public class CosaCrossover : PermutationCrossover {
40    [StorableConstructor]
41    protected CosaCrossover(StorableConstructorFlag _) : base(_) { }
42    protected CosaCrossover(CosaCrossover original, Cloner cloner) : base(original, cloner) { }
43    public CosaCrossover() : base() { }
44
45    public override IDeepCloneable Clone(Cloner cloner) {
46      return new CosaCrossover(this, cloner);
47    }
48
49    /// <summary>
50    /// The operator actually performs a 2-opt mutation on the first parent, but it uses the second parent to determine which new edge should be inserted.
51    /// Thus the mutation is not random as the second breakpoint depends on the information that is encoded in other members of the population.
52    /// The idea is that the child should not sit right inbetween the two parents, but rather go a little bit from one parent in direction to the other.
53    /// </summary>
54    /// <exception cref="ArgumentException">Thrown when <paramref name="parent1"/> and <paramref name="parent2"/> are not of equal length.</exception>
55    /// <param name="random">The random number generator.</param>
56    /// <param name="parent1">The parent scope 1 to cross over.</param>
57    /// <param name="parent2">The parent scope 2 to cross over.</param>
58    /// <returns>The created cross over permutation as int array.</returns>
59    public static Permutation Apply(IRandom random, Permutation parent1, Permutation parent2) {
60      if (parent1.Length != parent2.Length) throw new ArgumentException("CosaCrossover: The parent permutations are of unequal length.");
61      int length = parent1.Length;
62      int[] result = new int[length];
63      int crossPoint, startIndex, endIndex;
64
65      crossPoint = random.Next(length);
66      startIndex = (crossPoint + 1) % length;
67
68      int i = 0;
69      while ((i < parent2.Length) && (parent2[i] != parent1[crossPoint])) {  // find index of cross point in second permutation
70        i++;
71      }
72      int newEdge = parent2[(i + 1) % length]; // the number that follows the cross point number in parent2 is the new edge that we want to insert
73      endIndex = 0;
74      while ((endIndex < parent1.Length) && (parent1[endIndex] != newEdge)) {  // find index of the new edge in the first permutation
75        endIndex++;
76      }
77
78      if (startIndex <= endIndex) {
79        // copy parent1 to child and reverse the order in between startIndex and endIndex
80        for (i = 0; i < parent1.Length; i++) {
81          if (i >= startIndex && i <= endIndex) {
82            result[i] = parent1[endIndex - i + startIndex];
83          } else {
84            result[i] = parent1[i];
85          }
86        }
87      } else { // startIndex > endIndex
88        for (i = 0; i < parent1.Length; i++) {
89          if (i >= startIndex || i <= endIndex) {
90            result[i] = parent1[(endIndex - i + startIndex + length) % length]; // add length to wrap around when dropping below index 0
91          } else {
92            result[i] = parent1[i];
93          }
94        }
95      }
96      return new Permutation(parent1.PermutationType, result);
97    }
98
99    /// <summary>
100    /// Checks number of parents and calls <see cref="Apply(IRandom, Permutation, Permutation)"/>.
101    /// </summary>
102    /// <exception cref="InvalidOperationException">Thrown if there are not exactly two parents.</exception>
103    /// <param name="random">A random number generator.</param>
104    /// <param name="parents">An array containing the two permutations that should be crossed.</param>
105    /// <returns>The newly created permutation, resulting from the crossover operation.</returns>
106    protected override Permutation Cross(IRandom random, ItemArray<Permutation> parents) {
107      if (parents.Length != 2) throw new InvalidOperationException("CosaCrossover: The number of parents is not equal to 2");
108      return Apply(random, parents[0], parents[1]);
109    }
110  }
111}
Note: See TracBrowser for help on using the repository browser.