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source: trunk/sources/HeuristicLab.Problems.VehicleRouting/3.3/Encodings/Potvin/Crossovers/SequenceBasedCrossover.cs @ 4206

Last change on this file since 4206 was 4206, checked in by svonolfe, 14 years ago

Updated naming and description of the VRP operators (#1039)

File size: 3.0 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2010 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 HeuristicLab.Core;
23using HeuristicLab.Encodings.PermutationEncoding;
24using HeuristicLab.Parameters;
25using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
26using HeuristicLab.Data;
27
28namespace HeuristicLab.Problems.VehicleRouting.Encodings.Potvin {
29  [Item("SequenceBasedCrossover", "The SBX crossover for a VRP representations.  It is implemented as described in Potvin, J.-Y. and Bengio, S. (1996). The Vehicle Routing Problem with Time Windows - Part II: Genetic Search. INFORMS Journal of Computing, 8:165–172.")]
30  [StorableClass]
31  public sealed class SequenceBasedCrossover : PotvinCrossover {
32    [StorableConstructor]
33    private SequenceBasedCrossover(bool deserializing) : base(deserializing) { }
34
35    public SequenceBasedCrossover()
36      : base() { }
37       
38    protected override PotvinEncoding Crossover(IRandom random, PotvinEncoding parent1, PotvinEncoding parent2) {
39      PotvinEncoding child = parent1.Clone() as PotvinEncoding;
40      Tour newTour = new Tour();
41
42      int breakPoint1 = random.Next(1, Cities + 1);
43      Tour tour1 = FindRoute(child, breakPoint1);
44      breakPoint1 = tour1.Cities.IndexOf(breakPoint1);
45
46      for (int i = 0; i < breakPoint1; i++)
47        newTour.Cities.Add(tour1.Cities[i]);
48
49      int breakPoint2 = random.Next(1, Cities + 1);
50      Tour tour2 = FindRoute(parent2, breakPoint2);
51      breakPoint2 = tour2.Cities.IndexOf(breakPoint2);
52
53      for (int i = breakPoint2; i < tour2.Cities.Count; i++)
54        newTour.Cities.Add(tour2.Cities[i]);
55
56      child.Tours.Remove(tour1);
57      child.Tours.Add(newTour);
58
59      foreach (int city in tour1.Cities)
60        if (FindRoute(child, city) == null && !child.Unrouted.Contains(city))
61          child.Unrouted.Add(city);
62
63      foreach (int city in tour2.Cities)
64        if (FindRoute(child, city) == null && !child.Unrouted.Contains(city))
65          child.Unrouted.Add(city);
66
67      if (Feasible(newTour) &&
68          Repair(random, child, newTour)) {
69        return child;
70      } else {
71        if (random.NextDouble() < 0.5)
72          return parent1.Clone() as PotvinEncoding;
73        else
74          return parent2.Clone() as PotvinEncoding;
75      }
76    }
77  }
78}
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