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source: trunk/sources/HeuristicLab.Problems.VehicleRouting/3.3/Encodings/Potvin/Crossovers/PotvinSBXCrossover.cs @ 4177

Last change on this file since 4177 was 4177, checked in by svonolfe, 12 years ago

Refactored VRP in preparation for the code review (#1039)

File size: 3.1 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("PotvinSBXCrossover", "The SBX crossover for the Potvin 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 PotvinSBXCrossover : PotvinCrossover {
32    private Tour FindRoute(PotvinEncoding solution, int city) {
33      Tour found = null;
34
35      foreach (Tour tour in solution.Tours) {
36        if (tour.Cities.Contains(city)) {
37          found = tour;
38          break;
39        }
40      }
41
42      return found;
43    }
44   
45    protected override PotvinEncoding Crossover(IRandom random, PotvinEncoding parent1, PotvinEncoding parent2) {
46      PotvinEncoding child = parent1.Clone() as PotvinEncoding;
47      Tour newTour = new Tour();
48
49      int breakPoint1 = random.Next(1, Cities + 1);
50      Tour tour1 = FindRoute(child, breakPoint1);
51      breakPoint1 = tour1.Cities.IndexOf(breakPoint1);
52
53      for (int i = 0; i < breakPoint1; i++)
54        newTour.Cities.Add(tour1.Cities[i]);
55
56      int breakPoint2 = random.Next(1, Cities + 1);
57      Tour tour2 = FindRoute(parent2, breakPoint2);
58      breakPoint2 = tour2.Cities.IndexOf(breakPoint2);
59
60      for (int i = breakPoint2; i < tour2.Cities.Count; i++)
61        newTour.Cities.Add(tour2.Cities[i]);
62
63      child.Tours.Remove(tour1);
64      child.Tours.Add(newTour);
65
66      foreach (int city in tour1.Cities)
67        if (FindRoute(child, city) == null && !child.Unrouted.Contains(city))
68          child.Unrouted.Add(city);
69
70      foreach (int city in tour2.Cities)
71        if (FindRoute(child, city) == null && !child.Unrouted.Contains(city))
72          child.Unrouted.Add(city);
73
74      if (Repair(random, child, newTour))
75        return child;
76      else {
77        if(random.NextDouble() < 0.5)
78          return parent1.Clone() as PotvinEncoding;
79        else
80          return parent2.Clone() as PotvinEncoding;
81      }
82    }
83  }
84}
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