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source: trunk/sources/HeuristicLab.Operators/StochasticMultiBranch.cs @ 899

Last change on this file since 899 was 801, checked in by vdorfer, 16 years ago

Created API documentation for HeuristicLab.Operators namespace (#331)

File size: 3.6 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2008 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.Text;
25using HeuristicLab.Core;
26using HeuristicLab.Data;
27
28namespace HeuristicLab.Operators {
29  /// <summary>
30  /// Branch of operators that have different probabilities to get executed.
31  /// </summary>
32  public class StochasticMultiBranch : OperatorBase {
33    ///<inheritdoc select="summary"/>
34    public override string Description {
35      get { return @"TODO\r\nOperator description still missing ..."; }
36    }
37
38    /// <summary>
39    /// Initializes a new instance of <see cref="StochasticMultiBranch"/> with two variable infos
40    /// (<c>Probabilities</c> and <c>Random</c>).
41    /// </summary>
42    public StochasticMultiBranch()
43      : base() {
44      AddVariableInfo(new VariableInfo("Probabilities", "The probabilities, that define how likely each suboperator/graph is executed. This array must sum to 1", typeof(DoubleArrayData), VariableKind.In));
45      AddVariableInfo(new VariableInfo("Random", "The pseudo random-generator, used for any random-decision.", typeof(IRandom), VariableKind.In));
46    }
47
48    /// <summary>
49    /// Applies an operator of the branches to the specified <paramref name="scope"/> with a
50    /// specific probability.
51    /// </summary>
52    /// <exception cref="InvalidOperationException">Thrown when the list of probabilites does not
53    /// match the number of operators or if there was another problem with the list of probabilities.</exception>
54    /// <param name="scope">The scope to apply the operators on.</param>
55    /// <returns>A new <see cref="AtomicOperation"/> with a specific operator, depending
56    /// on its probability, applied on the given <paramref name="scope"/>.</returns>
57    public override IOperation Apply(IScope scope) {
58      IRandom random = GetVariableValue<IRandom>("Random", scope, true);
59      DoubleArrayData probabilities = GetVariableValue<DoubleArrayData>("Probabilities", scope, true);
60      if(probabilities.Data.Length != SubOperators.Count) {
61        throw new InvalidOperationException("StochasticMultiBranch: The list of probabilities has to match the number of operators");
62      }
63      double sum = 0;
64      foreach(double prob in probabilities.Data) {
65        sum+=prob;
66      }
67      double r = random.NextDouble()*sum;
68      sum = 0;
69      IOperator successor = null;
70      for(int i = 0; i < SubOperators.Count; i++) {
71        sum += probabilities.Data[i];
72        if(sum > r) {
73          successor = SubOperators[i];
74          break;
75        }
76      }
77      if(successor == null) {
78        throw new InvalidOperationException("StochasticMultiBranch: There was a problem with the list of probabilities");
79      }
80      return new AtomicOperation(successor, scope);
81    }
82  }
83}
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