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source: branches/RemoveBackwardsCompatibility/HeuristicLab.Problems.Knapsack/3.3/PathRelinkers/KnapsackSimultaneousPathRelinker.cs @ 14778

Last change on this file since 14778 was 12012, checked in by ascheibe, 10 years ago

#2212 merged r12008, r12009, r12010 back into trunk

File size: 4.3 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2015 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.BinaryVectorEncoding;
29using HeuristicLab.Optimization.Operators;
30using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
31
32namespace HeuristicLab.Problems.Knapsack {
33  /// <summary>
34  /// An operator that relinks paths between knapsack solutions starting from both ends.
35  /// </summary>
36  /// <remarks>
37  /// The operator incrementally assimilates the initiating solution into the guiding solution and vice versa by adding and removing elements as needed.
38  /// </remarks>
39  [Item("KnapsackSimultaneousPathRelinker", "An operator that relinks paths between knapsack solutions starting from both ends. The operator incrementally assimilates the initiating solution into the guiding solution and vice versa by adding and removing elements as needed.")]
40  [StorableClass]
41  public sealed class KnapsackSimultaneousPathRelinker : SingleObjectivePathRelinker {
42    [StorableConstructor]
43    private KnapsackSimultaneousPathRelinker(bool deserializing) : base(deserializing) { }
44    private KnapsackSimultaneousPathRelinker(KnapsackSimultaneousPathRelinker original, Cloner cloner) : base(original, cloner) { }
45    public KnapsackSimultaneousPathRelinker() : base() { }
46
47    public override IDeepCloneable Clone(Cloner cloner) {
48      return new KnapsackSimultaneousPathRelinker(this, cloner);
49    }
50
51    public static ItemArray<IItem> Apply(IItem initiator, IItem guide, PercentValue n) {
52      if (!(initiator is BinaryVector) || !(guide is BinaryVector))
53        throw new ArgumentException("Cannot relink path because one of the provided solutions or both have the wrong type.");
54      if (n.Value <= 0.0)
55        throw new ArgumentException("RelinkingAccuracy must be greater than 0.");
56
57      BinaryVector firstInitiator = initiator.Clone() as BinaryVector;
58      BinaryVector firstGuide = guide.Clone() as BinaryVector;
59      BinaryVector secondInitiator = firstGuide.Clone() as BinaryVector;
60      BinaryVector secondGuide = firstInitiator.Clone() as BinaryVector;
61
62      if (firstInitiator.Length != firstGuide.Length)
63        throw new ArgumentException("The solutions are of different length.");
64
65      IList<BinaryVector> solutions = new List<BinaryVector>();
66      for (int i = 0; i < firstInitiator.Length / 2; i++) {
67        if (firstInitiator[i] != firstGuide[i]) {
68          firstInitiator[i] = firstGuide[i];
69          solutions.Add(firstInitiator.Clone() as BinaryVector);
70        }
71        int j = secondInitiator.Length - 1 - i;
72        if (secondInitiator[j] != secondGuide[j]) {
73          secondInitiator[j] = secondGuide[j];
74          solutions.Add(secondInitiator.Clone() as BinaryVector);
75        }
76      }
77
78      IList<IItem> selection = new List<IItem>();
79      if (solutions.Count > 0) {
80        int noSol = (int)(solutions.Count * n.Value);
81        if (noSol <= 0) noSol++;
82        double stepSize = (double)solutions.Count / (double)noSol;
83        for (int i = 0; i < noSol; i++)
84          selection.Add(solutions.ElementAt((int)((i + 1) * stepSize - stepSize * 0.5)));
85      }
86
87      return new ItemArray<IItem>(selection);
88    }
89
90    protected override ItemArray<IItem> Relink(ItemArray<IItem> parents, PercentValue n) {
91      if (parents.Length != 2)
92        throw new ArgumentException("The number of parents is not equal to 2.");
93      return Apply(parents[0], parents[1], n);
94    }
95  }
96}
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