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source: branches/Scheduling/HeuristicLab.Encodings.RealVectorEncoding/3.3/Manipulators/BreederGeneticAlgorithmManipulator.cs @ 6319

Last change on this file since 6319 was 5445, checked in by swagner, 14 years ago

Updated year of copyrights (#1406)

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1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2011 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.Encodings.RealVectorEncoding {
30  /// <summary>
31  /// Changes one position of a real vector by adding/substracting a value of the interval [(2^-15)*range;~2*range], where range is SearchIntervalFactor * (max - min).
32  /// Note that the interval is not uniformly sampled, but smaller values are sampled more often.
33  /// </summary>
34  /// <remarks>
35  /// It is implemented as described by Mühlenbein, H. and Schlierkamp-Voosen, D. 1993. Predictive Models for the Breeder Genetic Algorithm - I. Continuous Parameter Optimization. Evolutionary Computation, 1(1), pp. 25-49.<br/>
36  /// </remarks>
37  [Item("BreederGeneticAlgorithmManipulator", "It is implemented as described by Mühlenbein, H. and Schlierkamp-Voosen, D. 1993. Predictive Models for the Breeder Genetic Algorithm - I. Continuous Parameter Optimization. Evolutionary Computation, 1(1), pp. 25-49.")]
38  [StorableClass]
39  public class BreederGeneticAlgorithmManipulator : RealVectorManipulator {
40    private static readonly double[] powerOfTwo = new double[] { 1, 0.5, 0.25, 0.125, 0.0625, 0.03125, 0.015625, 0.0078125, 0.00390625, 0.001953125, 0.0009765625, 0.00048828125, 0.000244140625, 0.0001220703125, 0.00006103515625, 0.000030517578125 };
41    public ValueLookupParameter<DoubleValue> SearchIntervalFactorParameter {
42      get { return (ValueLookupParameter<DoubleValue>)Parameters["SearchIntervalFactor"]; }
43    }
44
45    [StorableConstructor]
46    protected BreederGeneticAlgorithmManipulator(bool deserializing) : base(deserializing) { }
47    protected BreederGeneticAlgorithmManipulator(BreederGeneticAlgorithmManipulator original, Cloner cloner) : base(original, cloner) { }
48    /// <summary>
49    /// Initializes a new instance of <see cref="BreederGeneticAlgorithmManipulator"/> with two
50    /// parameters (<c>Bounds</c> and <c>SearchIntervalFactor</c>).
51    /// </summary>
52    public BreederGeneticAlgorithmManipulator()
53      : base() {
54      Parameters.Add(new ValueLookupParameter<DoubleValue>("SearchIntervalFactor", "The factor determining the size of the search interval, that will be added/removed to/from the allele selected for manipulation. E.g. a value of 0.1 means 10% of the range will be maximally added/removed.", new DoubleValue(0.1)));
55    }
56
57    public override IDeepCloneable Clone(Cloner cloner) {
58      return new BreederGeneticAlgorithmManipulator(this, cloner);
59    }
60
61    /// <summary>
62    /// Performs a breeder genetic algorithm manipulation on the given <paramref name="vector"/>.
63    /// </summary>
64    /// <param name="random">A random number generator.</param>
65    /// <param name="vector">The real vector to manipulate.</param>
66    /// <param name="bounds">The lower and upper bound (1st and 2nd column) of the positions in the vector. If there are less rows than dimensions, the rows are cycled.</param>
67    /// <param name="searchIntervalFactor">The factor determining the size of the search interval.</param>
68    public static void Apply(IRandom random, RealVector vector, DoubleMatrix bounds, DoubleValue searchIntervalFactor) {
69      int length = vector.Length;
70      double prob, value;
71      do {
72        value = Sigma(random);
73      } while (value == 0);
74
75      prob = 1.0 / (double)length;
76      bool wasMutated = false;
77
78      for (int i = 0; i < length; i++) {
79        if (random.NextDouble() < prob) {
80          double range = bounds[i % bounds.Rows, 1] - bounds[i % bounds.Rows, 0];
81          if (random.NextDouble() < 0.5) {
82            vector[i] = vector[i] + value * searchIntervalFactor.Value * range;
83          } else {
84            vector[i] = vector[i] - value * searchIntervalFactor.Value * range;
85          }
86          wasMutated = true;
87        }
88      }
89
90      // make sure at least one gene was mutated
91      if (!wasMutated) {
92        int pos = random.Next(length);
93        double range = bounds[pos % bounds.Rows, 1] - bounds[pos % bounds.Rows, 0];
94        if (random.NextDouble() < 0.5) {
95          vector[pos] = vector[pos] + value * searchIntervalFactor.Value * range;
96        } else {
97          vector[pos] = vector[pos] - value * searchIntervalFactor.Value * range;
98        }
99      }
100    }
101
102    private static double Sigma(IRandom random) {
103      double sigma = 0;
104      int limit = 16;
105
106      for (int i = 0; i < limit; i++) {
107        if (random.Next(limit) == 15) {
108          // execute this statement with a probability of 1/16
109          sigma += powerOfTwo[i];
110        }
111      }
112
113      return sigma;
114    }
115
116    /// <summary>
117    /// Checks the parameters Bounds, and SearchIntervalFactor and forwards the call to <see cref="Apply(IRandom, RealVector, DoubleValue, DoubleValue, DoubleValue)"/>.
118    /// </summary>
119    /// <param name="random">A random number generator.</param>
120    /// <param name="realVector">The real vector to manipulate.</param>
121    protected override void Manipulate(IRandom random, RealVector realVector) {
122      if (BoundsParameter.ActualValue == null) throw new InvalidOperationException("BreederGeneticAlgorithmManipulator: Parameter " + BoundsParameter.ActualName + " could not be found.");
123      if (SearchIntervalFactorParameter.ActualValue == null) throw new InvalidOperationException("BreederGeneticAlgorithmManipulator: Paraemter " + SearchIntervalFactorParameter.ActualName + " could not be found.");
124      Apply(random, realVector, BoundsParameter.ActualValue, SearchIntervalFactorParameter.ActualValue);
125    }
126  }
127}
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