source: branches/2839_HiveProjectManagement/HeuristicLab.Encodings.RealVectorEncoding/3.3/Manipulators/BreederGeneticAlgorithmManipulator.cs @ 16057

Last change on this file since 16057 was 16057, checked in by jkarder, 15 months ago

#2839:

File size: 6.4 KB
Line 
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.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", @"Scales the manipulation strength as a factor of the range. The range is determined by the bounds interval.
55A value of 0.1 means that certain components of the vector are moved by values in the non-uniform interval [0;0.1*range].", new DoubleValue(0.1)));
56    }
57
58    public override IDeepCloneable Clone(Cloner cloner) {
59      return new BreederGeneticAlgorithmManipulator(this, cloner);
60    }
61
62    /// <summary>
63    /// Performs a breeder genetic algorithm manipulation on the given <paramref name="vector"/>.
64    /// </summary>
65    /// <param name="random">A random number generator.</param>
66    /// <param name="vector">The real vector to manipulate.</param>
67    /// <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>
68    /// <param name="searchIntervalFactor">The factor determining the size of the search interval.</param>
69    public static void Apply(IRandom random, RealVector vector, DoubleMatrix bounds, DoubleValue searchIntervalFactor) {
70      int length = vector.Length;
71      double prob, value;
72      do {
73        value = Sigma(random);
74      } while (value == 0);
75
76      prob = 1.0 / (double)length;
77      bool wasMutated = false;
78
79      for (int i = 0; i < length; i++) {
80        if (random.NextDouble() < prob) {
81          double range = bounds[i % bounds.Rows, 1] - bounds[i % bounds.Rows, 0];
82          if (random.NextDouble() < 0.5) {
83            vector[i] = vector[i] + value * searchIntervalFactor.Value * range;
84          } else {
85            vector[i] = vector[i] - value * searchIntervalFactor.Value * range;
86          }
87          wasMutated = true;
88        }
89      }
90
91      // make sure at least one gene was mutated
92      if (!wasMutated) {
93        int pos = random.Next(length);
94        double range = bounds[pos % bounds.Rows, 1] - bounds[pos % bounds.Rows, 0];
95        if (random.NextDouble() < 0.5) {
96          vector[pos] = vector[pos] + value * searchIntervalFactor.Value * range;
97        } else {
98          vector[pos] = vector[pos] - value * searchIntervalFactor.Value * range;
99        }
100      }
101    }
102
103    private static double Sigma(IRandom random) {
104      double sigma = 0;
105      int limit = 16;
106
107      for (int i = 0; i < limit; i++) {
108        if (random.Next(limit) == 15) {
109          // execute this statement with a probability of 1/16
110          sigma += powerOfTwo[i];
111        }
112      }
113
114      return sigma;
115    }
116
117    /// <summary>
118    /// Checks the parameters Bounds, and SearchIntervalFactor and forwards the call to <see cref="Apply(IRandom, RealVector, DoubleValue, DoubleValue, DoubleValue)"/>.
119    /// </summary>
120    /// <param name="random">A random number generator.</param>
121    /// <param name="realVector">The real vector to manipulate.</param>
122    protected override void Manipulate(IRandom random, RealVector realVector) {
123      if (BoundsParameter.ActualValue == null) throw new InvalidOperationException("BreederGeneticAlgorithmManipulator: Parameter " + BoundsParameter.ActualName + " could not be found.");
124      if (SearchIntervalFactorParameter.ActualValue == null) throw new InvalidOperationException("BreederGeneticAlgorithmManipulator: Paraemter " + SearchIntervalFactorParameter.ActualName + " could not be found.");
125      Apply(random, realVector, BoundsParameter.ActualValue, SearchIntervalFactorParameter.ActualValue);
126    }
127  }
128}
Note: See TracBrowser for help on using the repository browser.