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source: trunk/sources/HeuristicLab.Problems.Knapsack/3.3/PathRelinkers/KnapsackPathRelinker.cs @ 8943

Last change on this file since 8943 was 8327, checked in by jkarder, 12 years ago

#1331: applied the rest of the changes suggested by ascheibe in comment:32:ticket:1331

File size: 3.7 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.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.
35  /// </summary>
36  /// <remarks>
37  /// The operator incrementally assimilates the initiating solution into the guiding solution by adding and removing elements as needed.
38  /// </remarks>
39  [Item("KnapsackPathRelinker", "An operator that relinks paths between knapsack solutions. The operator incrementally assimilates the initiating solution into the guiding solution by adding and removing elements as needed.")]
40  [StorableClass]
41  public sealed class KnapsackPathRelinker : SingleObjectivePathRelinker {
42    [StorableConstructor]
43    private KnapsackPathRelinker(bool deserializing) : base(deserializing) { }
44    private KnapsackPathRelinker(KnapsackPathRelinker original, Cloner cloner) : base(original, cloner) { }
45    public KnapsackPathRelinker() : base() { }
46
47    public override IDeepCloneable Clone(Cloner cloner) {
48      return new KnapsackPathRelinker(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 v1 = initiator.Clone() as BinaryVector;
58      BinaryVector v2 = guide as BinaryVector;
59
60      if (v1.Length != v2.Length)
61        throw new ArgumentException("The solutions are of different length.");
62
63      IList<BinaryVector> solutions = new List<BinaryVector>();
64      for (int i = 0; i < v1.Length; i++)
65        if (v1[i] != v2[i]) {
66          v1[i] = v2[i];
67          solutions.Add(v1.Clone() as BinaryVector);
68        }
69
70      IList<IItem> selection = new List<IItem>();
71      if (solutions.Count > 0) {
72        int noSol = (int)(solutions.Count * n.Value);
73        if (noSol <= 0) noSol++;
74        double stepSize = (double)solutions.Count / (double)noSol;
75        for (int i = 0; i < noSol; i++)
76          selection.Add(solutions.ElementAt((int)((i + 1) * stepSize - stepSize * 0.5)));
77      }
78
79      return new ItemArray<IItem>(selection);
80    }
81
82    protected override ItemArray<IItem> Relink(ItemArray<IItem> parents, PercentValue n) {
83      if (parents.Length != 2)
84        throw new ArgumentException("The number of parents is not equal to 2.");
85      return Apply(parents[0], parents[1], n);
86    }
87  }
88}
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