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source: branches/ScatterSearch/HeuristicLab.Algorithms.ScatterSearch/3.3/TravelingSalesman/TravelingSalesmanPathRelinker.cs @ 7775

Last change on this file since 7775 was 7775, checked in by jkarder, 12 years ago

#1331:

  • added operators for TestFunctions problems
  • added more path relinking operators for the TravelingSalesman and the Knapsack problem
  • added 2-tier version of the SolutionPoolUpdateMethod
  • added parameters and adjusted types
  • added some exception handling
  • adjusted event handling
  • updated plugin dependencies
  • minor code improvements
File size: 3.8 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2012 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 System.Collections.Generic;
24using System.Linq;
25using HeuristicLab.Common;
26using HeuristicLab.Core;
27using HeuristicLab.Data;
28using HeuristicLab.Encodings.PermutationEncoding;
29using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
30
31namespace HeuristicLab.Algorithms.ScatterSearch.TravelingSalesman {
32  /// <summary>
33  /// An operator that relinks paths between traveling salesman solutions.
34  /// </summary>
35  [Item("TravelingSalesmanPathRelinker", "An operator that relinks paths between traveling salesman solutions.")]
36  [StorableClass]
37  public sealed class TravelingSalesmanPathRelinker : PathRelinker {
38    [StorableConstructor]
39    private TravelingSalesmanPathRelinker(bool deserializing) : base(deserializing) { }
40    private TravelingSalesmanPathRelinker(TravelingSalesmanPathRelinker original, Cloner cloner) : base(original, cloner) { }
41    public TravelingSalesmanPathRelinker()
42      : base() {
43      ParentsParameter.ActualName = "TSPTour";
44    }
45
46    public override IDeepCloneable Clone(Cloner cloner) {
47      return new TravelingSalesmanPathRelinker(this, cloner);
48    }
49
50    public static ItemArray<IItem> Apply(IItem initiator, IItem guide, PercentValue n) {
51      if (!(initiator is Permutation) || !(guide is Permutation))
52        throw new ArgumentException("Cannot relink path because one of the provided solutions or both have the wrong type.");
53      if (n.Value <= 0.0)
54        throw new ArgumentException("RelinkingAccuracy must be greater than 0.");
55
56      var v1 = initiator.Clone() as Permutation;
57      var v2 = guide as Permutation;
58
59      if (v1.Length != v2.Length)
60        throw new ArgumentException("The solutions are of different length.");
61
62      var solutions = new List<Permutation>();
63      for (int i = 0; i < v1.Length; i++)
64        if (v1[i] != v2[i]) {
65          var target = v1.Select((x, index) => new { Value = x, ValueIndex = index }).First(x => x.Value == v2[i]);
66          if (v1[i] != v1[target.ValueIndex]) {
67            // XOR swap
68            v1[i] ^= v1[target.ValueIndex];
69            v1[target.ValueIndex] ^= v1[i];
70            v1[i] ^= v1[target.ValueIndex];
71            solutions.Add(v1.Clone() as Permutation);
72          }
73        }
74
75      var selection = new List<IItem>();
76      if (solutions.Count > 0) {
77        var noSol = (int)Math.Round(solutions.Count * n.Value);
78        if (noSol <= 0) noSol++;
79        var stepSize = (double)solutions.Count / (double)noSol;
80        for (int i = 0; i < noSol; i++)
81          selection.Add(solutions.ElementAt((int)Math.Round((i + 1) * stepSize - stepSize * 0.5)));
82      }
83
84      return new ItemArray<IItem>(selection);
85    }
86
87    protected override ItemArray<IItem> Relink(ItemArray<IItem> parents, PercentValue n) {
88      if (parents.Length != 2)
89        throw new ArgumentException("The number of parents is not equal to 2.");
90      return Apply(parents[0], parents[1], n);
91    }
92  }
93}
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