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source: trunk/sources/HeuristicLab.Optimization.Operators/3.3/ProbabilisticQualityComparator.cs @ 15675

Last change on this file since 15675 was 15583, checked in by swagner, 7 years ago

#2640: Updated year of copyrights in license headers

File size: 3.2 KB
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1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2018 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 HeuristicLab.Common;
24using HeuristicLab.Core;
25using HeuristicLab.Data;
26using HeuristicLab.Parameters;
27using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
28
29namespace HeuristicLab.Optimization.Operators {
30  /// <summary>
31  /// Compares two qualities and creates a boolean flag that indicates if the left side is better than the right side or if the difference in quality is acceptable given a certain probability.
32  /// </summary>
33  /// <remarks>
34  /// The probabilty is that of simulated annealing: A randomly drawn (uniformly) real value in
35  /// the interval [0;1) has to be smaller than e^(-diff/T) where diff is the absolute quality difference
36  /// and T is the temperature (here called dampening).
37  /// </remarks>
38  [Item("ProbabilisticQualityComparator", "Compares two qualities and creates a boolean flag that indicates if the left side is better than the right side or if the difference in quality is acceptable given a certain probability.")]
39  [StorableClass]
40  public class ProbabilisticQualityComparator : QualityComparator, IStochasticOperator {
41    public ILookupParameter<DoubleValue> DampeningParameter {
42      get { return (ILookupParameter<DoubleValue>)Parameters["Dampening"]; }
43    }
44    public ILookupParameter<IRandom> RandomParameter {
45      get { return (ILookupParameter<IRandom>)Parameters["Random"]; }
46    }
47
48    [StorableConstructor]
49    protected ProbabilisticQualityComparator(bool deserializing) : base(deserializing) { }
50    protected ProbabilisticQualityComparator(ProbabilisticQualityComparator original, Cloner cloner) : base(original, cloner) { }
51    public ProbabilisticQualityComparator()
52      : base() {
53      Parameters.Add(new LookupParameter<DoubleValue>("Dampening", "The dampening factor that influences the probability."));
54      Parameters.Add(new LookupParameter<IRandom>("Random", "The random number generator."));
55    }
56
57    public override IDeepCloneable Clone(Cloner cloner) {
58      return new ProbabilisticQualityComparator(this, cloner);
59    }
60
61    protected override bool Compare(bool maximization, double left, double right) {
62      if (base.Compare(maximization, left, right)) return true;
63      double t = DampeningParameter.ActualValue.Value;
64      double probability = Math.Exp(-Math.Abs(left - right) / t);
65      return RandomParameter.ActualValue.NextDouble() < probability;
66    }
67  }
68}
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