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source: trunk/sources/HeuristicLab.Selection/3.3/TournamentSelector.cs @ 2895

Last change on this file since 2895 was 2830, checked in by swagner, 15 years ago

Operator architecture refactoring (#95)

  • worked on operators and SGA
  • improved performance
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 System.Collections.Generic;
23using System.Linq;
24using HeuristicLab.Core;
25using HeuristicLab.Data;
26using HeuristicLab.Parameters;
27using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
28
29namespace HeuristicLab.Selection {
30  /// <summary>
31  /// A tournament selection operator which considers a single double quality value for selection.
32  /// </summary>
33  [Item("TournamentSelector", "A tournament selection operator which considers a single double quality value for selection.")]
34  [EmptyStorableClass]
35  [Creatable("Test")]
36  public sealed class TournamentSelector : StochasticSingleObjectiveSelector {
37    public ValueLookupParameter<IntData> GroupSizeParameter {
38      get { return (ValueLookupParameter<IntData>)Parameters["GroupSize"]; }
39    }
40
41    public TournamentSelector() : base() {
42      Parameters.Add(new ValueLookupParameter<IntData>("GroupSize", "The size of the tournament group.", new IntData(2)));
43      CopySelected.Value = true;
44    }
45
46    protected override IScope[] Select(List<IScope> scopes) {
47      int count = NumberOfSelectedSubScopesParameter.ActualValue.Value;
48      bool copy = CopySelectedParameter.Value.Value;
49      IRandom random = RandomParameter.ActualValue;
50      bool maximization = MaximizationParameter.ActualValue.Value;
51      List<double> qualities = QualityParameter.ActualValue.Select(x => x.Value).ToList();
52      int groupSize = GroupSizeParameter.ActualValue.Value;
53      IScope[] selected = new IScope[count];
54
55      for (int i = 0; i < count; i++) {
56        int best = random.Next(scopes.Count);
57        int index;
58        for (int j = 1; j < groupSize; j++) {
59          index = random.Next(scopes.Count);
60          if (((maximization) && (qualities[index] > qualities[best])) ||
61              ((!maximization) && (qualities[index] < qualities[best]))) {
62            best = index;
63          }
64        }
65
66        if (copy)
67          selected[i] = (IScope)scopes[best].Clone();
68        else {
69          selected[i] = scopes[best];
70          scopes.RemoveAt(best);
71          qualities.RemoveAt(best);
72        }
73      }
74      return selected;
75    }
76  }
77}
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