source: branches/2520_PersistenceReintegration/HeuristicLab.Encodings.PermutationEncoding/3.3/Crossovers/OrderCrossover.cs @ 16453

Last change on this file since 16453 was 16453, checked in by jkarder, 10 months ago

#2520: updated year of copyrights

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1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2019 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.PermutationEncoding {
28  /// <summary>
29  /// An operator which performs the order crossover on two permutations.
30  /// </summary>
31  /// <remarks>
32  /// It is implemented as described in Eiben, A.E. and Smith, J.E. 2003. Introduction to Evolutionary Computation. Natural Computing Series, Springer-Verlag Berlin Heidelberg.<br />
33  /// Crosses two permutations by copying a randomly chosen interval from the first permutation, preserving
34  /// the positions. Then, starting from the end of the copied interval, copies the missing values from the second permutation
35  /// in the order they occur.
36  /// </remarks>
37  [Item("OrderCrossover", "An operator which performs an order crossover of two permutations. It is implemented as described in Eiben, A.E. and Smith, J.E. 2003. Introduction to Evolutionary Computation. Natural Computing Series, Springer-Verlag Berlin Heidelberg.")]
38  [StorableClass]
39  public class OrderCrossover : PermutationCrossover {
40    [StorableConstructor]
41    protected OrderCrossover(bool deserializing) : base(deserializing) { }
42    protected OrderCrossover(OrderCrossover original, Cloner cloner) : base(original, cloner) { }
43    public OrderCrossover() : base() { }
44
45    public override IDeepCloneable Clone(Cloner cloner) {
46      return new OrderCrossover(this, cloner);
47    }
48
49    /// <summary>
50    /// Performs the order crossover of two permutations.
51    /// </summary>
52    /// <exception cref="ArgumentException">Thrown when <paramref name="parent1"/> and <paramref name="parent2"/> are not of equal length.</exception>
53    /// <exception cref="InvalidOperationException">Thrown if the numbers in the permutation elements are not in the range [0,N) with N = length of the permutation.</exception>
54    /// <remarks>
55    /// Crosses two permutations by copying a randomly chosen interval from the first permutation, preserving
56    /// the positions. Then, starting from the end of the copied interval, copies the missing values from the second permutation
57    /// in the order they occur.
58    /// </remarks>
59    /// <param name="random">A random number generator.</param>
60    /// <param name="parent1">The first parent permutation to cross.</param>
61    /// <param name="parent2">The second parent permutation to cross.</param>
62    /// <returns>The new permutation resulting from the crossover.</returns>
63    public static Permutation Apply(IRandom random, Permutation parent1, Permutation parent2) {
64      if (parent1.Length != parent2.Length) throw new ArgumentException("OrderCrossover: The parent permutations are of unequal length.");
65      int length = parent1.Length;
66      int[] result = new int[length];
67      bool[] copied = new bool[length];
68
69      int breakPoint1 = random.Next(length - 1);
70      int breakPoint2 = random.Next(breakPoint1 + 1, length);
71
72      try {
73        for (int j = breakPoint1; j <= breakPoint2; j++) {  // copy part of first permutation
74          result[j] = parent1[j];
75          copied[parent1[j]] = true;
76        }
77
78        int index = ((breakPoint2 + 1 >= length) ? (0) : (breakPoint2 + 1));
79        int i = index; // for moving in parent2
80        while (index != breakPoint1) {
81          if (!copied[parent2[i]]) {
82            result[index] = parent2[i];
83            index++;
84            if (index >= length) index = 0;
85          }
86          i++;
87          if (i >= length) i = 0;
88        }
89      }
90      catch (IndexOutOfRangeException) {
91        throw new InvalidOperationException("OrderCrossover: The permutation must consist of numbers in the interval [0;N) with N = length of the permutation.");
92      }
93      return new Permutation(parent1.PermutationType, result);
94    }
95
96    /// <summary>
97    /// Checks number of parents and calls <see cref="Apply(IRandom, Permutation, Permutation)"/>.
98    /// </summary>
99    /// <exception cref="InvalidOperationException">Thrown if there are not exactly two parents.</exception>
100    /// <param name="random">A random number generator.</param>
101    /// <param name="parents">An array containing the two permutations that should be crossed.</param>
102    /// <returns>The new permutation resulting from the crossover.</returns>
103    protected override Permutation Cross(IRandom random, ItemArray<Permutation> parents) {
104      if (parents.Length != 2) throw new InvalidOperationException("OrderCrossover: Number of parents is not equal to 2.");
105      return Apply(random, parents[0], parents[1]);
106    }
107  }
108}
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