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source: trunk/sources/HeuristicLab.Algorithms.TabuSearch/3.3/TabuSelector.cs @ 4767

Last change on this file since 4767 was 4722, checked in by swagner, 14 years ago

Merged cloning refactoring branch back into trunk (#922)

File size: 7.3 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.Common;
25using HeuristicLab.Core;
26using HeuristicLab.Data;
27using HeuristicLab.Parameters;
28using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
29using HeuristicLab.Selection;
30
31namespace HeuristicLab.Algorithms.TabuSearch {
32  /// <summary>
33  /// 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.
34  /// </summary>
35  /// <remarks>
36  /// For different aspiration criteria a new operator should be implemented.
37  /// </remarks>
38  [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).")]
39  [StorableClass]
40  public class TabuSelector : Selector {
41    /// <summary>
42    /// The best found quality so far.
43    /// </summary>
44    public LookupParameter<DoubleValue> BestQualityParameter {
45      get { return (LookupParameter<DoubleValue>)Parameters["BestQuality"]; }
46    }
47    /// <summary>
48    /// Whether to use the default aspiration criteria or not.
49    /// </summary>
50    public ValueLookupParameter<BoolValue> AspirationParameter {
51      get { return (ValueLookupParameter<BoolValue>)Parameters["Aspiration"]; }
52    }
53    /// <summary>
54    /// Whether the problem is a maximization problem or not.
55    /// </summary>
56    public IValueLookupParameter<BoolValue> MaximizationParameter {
57      get { return (IValueLookupParameter<BoolValue>)Parameters["Maximization"]; }
58    }
59    /// <summary>
60    /// The parameter for the move qualities.
61    /// </summary>
62    public ILookupParameter<ItemArray<DoubleValue>> MoveQualityParameter {
63      get { return (ILookupParameter<ItemArray<DoubleValue>>)Parameters["MoveQuality"]; }
64    }
65    /// <summary>
66    /// The parameter for the tabu status of the moves.
67    /// </summary>
68    public ILookupParameter<ItemArray<BoolValue>> MoveTabuParameter {
69      get { return (ILookupParameter<ItemArray<BoolValue>>)Parameters["MoveTabu"]; }
70    }
71    public IValueLookupParameter<BoolValue> CopySelectedParameter {
72      get { return (IValueLookupParameter<BoolValue>)Parameters["CopySelected"]; }
73    }
74    public ILookupParameter<BoolValue> EmptyNeighborhoodParameter {
75      get { return (ILookupParameter<BoolValue>)Parameters["EmptyNeighborhood"]; }
76    }
77
78    public BoolValue CopySelected {
79      get { return CopySelectedParameter.Value; }
80      set { CopySelectedParameter.Value = value; }
81    }
82
83    [StorableConstructor]
84    protected TabuSelector(bool deserializing) : base(deserializing) { }
85    protected TabuSelector(TabuSelector original, Cloner cloner)
86      : base(original, cloner) {
87    }
88    public override IDeepCloneable Clone(Cloner cloner) {
89      return new TabuSelector(this, cloner);
90    }
91
92    /// <summary>
93    /// Initializes a new intsance with 6 parameters (<c>Quality</c>, <c>BestQuality</c>,
94    /// <c>Aspiration</c>, <c>Maximization</c>, <c>MoveQuality</c>, and <c>MoveTabu</c>).
95    /// </summary>
96    public TabuSelector()
97      : base() {
98      Parameters.Add(new LookupParameter<DoubleValue>("BestQuality", "The best found quality so far."));
99      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)));
100      Parameters.Add(new ValueLookupParameter<BoolValue>("Maximization", "Whether the problem is a maximization or minimization problem (used to decide whether a solution is better"));
101      Parameters.Add(new ScopeTreeLookupParameter<DoubleValue>("MoveQuality", "The quality of the move."));
102      Parameters.Add(new ScopeTreeLookupParameter<BoolValue>("MoveTabu", "The tabu status of the move."));
103      Parameters.Add(new ValueLookupParameter<BoolValue>("CopySelected", "True if the selected move should be copied.", new BoolValue(false)));
104      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."));
105    }
106
107    /// <summary>
108    /// Implements the tabu selection with the default aspiration criteria (choose a tabu move when it is better than the best so far).
109    /// </summary>
110    /// <exception cref="InvalidOperationException">Thrown when the neighborhood contained too little moves which are not tabu.</exception>
111    /// <param name="scopes">The scopes from which to select.</param>
112    /// <returns>The selected scopes.</returns>
113    protected override IScope[] Select(List<IScope> scopes) {
114      bool copy = CopySelectedParameter.Value.Value;
115      bool aspiration = AspirationParameter.ActualValue.Value;
116      bool maximization = MaximizationParameter.ActualValue.Value;
117      double bestQuality = BestQualityParameter.ActualValue.Value;
118      ItemArray<DoubleValue> moveQualities = MoveQualityParameter.ActualValue;
119      ItemArray<BoolValue> moveTabus = MoveTabuParameter.ActualValue;
120
121      IScope[] selected = new IScope[1];
122
123      // remember scopes that should be removed
124      List<int> scopesToRemove = new List<int>();
125      for (int i = 0; i < scopes.Count; i++) {
126        if (!moveTabus[i].Value
127          || aspiration && IsBetter(maximization, moveQualities[i].Value, bestQuality)) {
128          scopesToRemove.Add(i);
129          if (copy) selected[0] = (IScope)scopes[i].Clone();
130          else selected[0] = scopes[i];
131          break;
132        }
133      }
134
135      if (selected[0] == null) {
136        EmptyNeighborhoodParameter.ActualValue = new BoolValue(true);
137        selected[0] = new Scope("All moves are tabu.");
138      } else EmptyNeighborhoodParameter.ActualValue = new BoolValue(false);
139
140      // remove from last to first so that the stored indices remain the same
141      if (!copy) {
142        while (scopesToRemove.Count > 0) {
143          scopes.RemoveAt(scopesToRemove[scopesToRemove.Count - 1]);
144          scopesToRemove.RemoveAt(scopesToRemove.Count - 1);
145        }
146      }
147
148      return selected;
149    }
150
151    private bool IsBetter(bool maximization, double moveQuality, double bestQuality) {
152      return (maximization && moveQuality > bestQuality || !maximization && moveQuality < bestQuality);
153    }
154  }
155}
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