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source: trunk/sources/HeuristicLab.Algorithms.TabuSearch/3.3/TabuSelector.cs @ 4485

Last change on this file since 4485 was 4068, checked in by swagner, 14 years ago

Sorted usings and removed unused usings in entire solution (#1094)

File size: 6.9 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;
23using System.Collections.Generic;
24using HeuristicLab.Core;
25using HeuristicLab.Data;
26using HeuristicLab.Parameters;
27using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
28using HeuristicLab.Selection;
29
30namespace HeuristicLab.Algorithms.TabuSearch {
31  /// <summary>
32  /// The tabu selector is a selection operator that separates the best n moves that are either not tabu or satisfy the default aspiration criterion from the rest. It expects the move subscopes to be sorted.
33  /// </summary>
34  /// <remarks>
35  /// For different aspiration criteria a new operator should be implemented.
36  /// </remarks>
37  [Item("TabuSelector", "An operator that selects the best move that is either not tabu or satisfies the aspiration criterion. It expects the move subscopes to be sorted by the qualities of the moves (the best move is first).")]
38  [StorableClass]
39  public class TabuSelector : Selector {
40    /// <summary>
41    /// The best found quality so far.
42    /// </summary>
43    public LookupParameter<DoubleValue> BestQualityParameter {
44      get { return (LookupParameter<DoubleValue>)Parameters["BestQuality"]; }
45    }
46    /// <summary>
47    /// Whether to use the default aspiration criteria or not.
48    /// </summary>
49    public ValueLookupParameter<BoolValue> AspirationParameter {
50      get { return (ValueLookupParameter<BoolValue>)Parameters["Aspiration"]; }
51    }
52    /// <summary>
53    /// Whether the problem is a maximization problem or not.
54    /// </summary>
55    public IValueLookupParameter<BoolValue> MaximizationParameter {
56      get { return (IValueLookupParameter<BoolValue>)Parameters["Maximization"]; }
57    }
58    /// <summary>
59    /// The parameter for the move qualities.
60    /// </summary>
61    public ILookupParameter<ItemArray<DoubleValue>> MoveQualityParameter {
62      get { return (ILookupParameter<ItemArray<DoubleValue>>)Parameters["MoveQuality"]; }
63    }
64    /// <summary>
65    /// The parameter for the tabu status of the moves.
66    /// </summary>
67    public ILookupParameter<ItemArray<BoolValue>> MoveTabuParameter {
68      get { return (ILookupParameter<ItemArray<BoolValue>>)Parameters["MoveTabu"]; }
69    }
70    public IValueLookupParameter<BoolValue> CopySelectedParameter {
71      get { return (IValueLookupParameter<BoolValue>)Parameters["CopySelected"]; }
72    }
73    public ILookupParameter<BoolValue> EmptyNeighborhoodParameter {
74      get { return (ILookupParameter<BoolValue>)Parameters["EmptyNeighborhood"]; }
75    }
76
77    public BoolValue CopySelected {
78      get { return CopySelectedParameter.Value; }
79      set { CopySelectedParameter.Value = value; }
80    }
81
82    /// <summary>
83    /// Initializes a new intsance with 6 parameters (<c>Quality</c>, <c>BestQuality</c>,
84    /// <c>Aspiration</c>, <c>Maximization</c>, <c>MoveQuality</c>, and <c>MoveTabu</c>).
85    /// </summary>
86    public TabuSelector()
87      : base() {
88      Parameters.Add(new LookupParameter<DoubleValue>("BestQuality", "The best found quality so far."));
89      Parameters.Add(new ValueLookupParameter<BoolValue>("Aspiration", "Whether the default aspiration criterion should be used or not. The default aspiration criterion accepts a tabu move if it results in a better solution than the best solution found so far.", new BoolValue(true)));
90      Parameters.Add(new ValueLookupParameter<BoolValue>("Maximization", "Whether the problem is a maximization or minimization problem (used to decide whether a solution is better"));
91      Parameters.Add(new ScopeTreeLookupParameter<DoubleValue>("MoveQuality", "The quality of the move."));
92      Parameters.Add(new ScopeTreeLookupParameter<BoolValue>("MoveTabu", "The tabu status of the move."));
93      Parameters.Add(new ValueLookupParameter<BoolValue>("CopySelected", "True if the selected move should be copied.", new BoolValue(false)));
94      Parameters.Add(new LookupParameter<BoolValue>("EmptyNeighborhood", "Will be set to true if the neighborhood didn't contain any non-tabu moves, otherwise it is set to false."));
95    }
96
97    /// <summary>
98    /// Implements the tabu selection with the default aspiration criteria (choose a tabu move when it is better than the best so far).
99    /// </summary>
100    /// <exception cref="InvalidOperationException">Thrown when the neighborhood contained too little moves which are not tabu.</exception>
101    /// <param name="scopes">The scopes from which to select.</param>
102    /// <returns>The selected scopes.</returns>
103    protected override IScope[] Select(List<IScope> scopes) {
104      bool copy = CopySelectedParameter.Value.Value;
105      bool aspiration = AspirationParameter.ActualValue.Value;
106      bool maximization = MaximizationParameter.ActualValue.Value;
107      double bestQuality = BestQualityParameter.ActualValue.Value;
108      ItemArray<DoubleValue> moveQualities = MoveQualityParameter.ActualValue;
109      ItemArray<BoolValue> moveTabus = MoveTabuParameter.ActualValue;
110
111      IScope[] selected = new IScope[1];
112
113      // remember scopes that should be removed
114      List<int> scopesToRemove = new List<int>();
115      for (int i = 0; i < scopes.Count; i++) {
116        if (!moveTabus[i].Value
117          || aspiration && IsBetter(maximization, moveQualities[i].Value, bestQuality)) {
118          scopesToRemove.Add(i);
119          if (copy) selected[0] = (IScope)scopes[i].Clone();
120          else selected[0] = scopes[i];
121          break;
122        }
123      }
124
125      if (selected[0] == null) {
126        EmptyNeighborhoodParameter.ActualValue = new BoolValue(true);
127        selected[0] = new Scope("All moves are tabu.");
128      } else EmptyNeighborhoodParameter.ActualValue = new BoolValue(false);
129
130      // remove from last to first so that the stored indices remain the same
131      if (!copy) {
132        while (scopesToRemove.Count > 0) {
133          scopes.RemoveAt(scopesToRemove[scopesToRemove.Count - 1]);
134          scopesToRemove.RemoveAt(scopesToRemove.Count - 1);
135        }
136      }
137
138      return selected;
139    }
140
141    private bool IsBetter(bool maximization, double moveQuality, double bestQuality) {
142      return (maximization && moveQuality > bestQuality || !maximization && moveQuality < bestQuality);
143    }
144  }
145}
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