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source: branches/OaaS/HeuristicLab.Problems.QuadraticAssignment/3.3/Evaluators/QAPSwap2MoveEvaluator.cs @ 12597

Last change on this file since 12597 was 7259, checked in by swagner, 13 years ago

Updated year of copyrights to 2012 (#1716)

File size: 6.9 KB
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1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2012 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.Encodings.PermutationEncoding;
27using HeuristicLab.Parameters;
28using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
29
30namespace HeuristicLab.Problems.QuadraticAssignment {
31  [Item("QAPSwap2MoveEvaluator", "Evaluated a swap-2 move on a QAP solution.")]
32  [StorableClass]
33  public class QAPSwap2MoveEvaluator : QAPMoveEvaluator, IPermutationSwap2MoveOperator {
34    public ILookupParameter<Swap2Move> Swap2MoveParameter {
35      get { return (ILookupParameter<Swap2Move>)Parameters["Swap2Move"]; }
36    }
37
38    [StorableConstructor]
39    protected QAPSwap2MoveEvaluator(bool deserializing) : base(deserializing) { }
40    protected QAPSwap2MoveEvaluator(QAPSwap2MoveEvaluator original, Cloner cloner)
41      : base(original, cloner) {
42    }
43    public QAPSwap2MoveEvaluator() {
44      Parameters.Add(new LookupParameter<Swap2Move>("Swap2Move", "The move to evaluate."));
45    }
46
47    public override IDeepCloneable Clone(Cloner cloner) {
48      return new QAPSwap2MoveEvaluator(this, cloner);
49    }
50
51    /// <summary>
52    /// Calculates the quality of the move <paramref name="move"/> by evaluating the changes.
53    /// The runtime complexity of this method is O(N) with N being the size of the permutation.
54    /// </summary>
55    /// <param name="assignment">The current permutation.</param>
56    /// <param name="move">The move that is to be evaluated if it was applied to the current permutation.</param>
57    /// <param name="weights">The weights matrix.</param>
58    /// <param name="distances">The distances matrix.</param>
59    /// <returns>The relative change in quality if <paramref name="move"/> was applied to <paramref name="assignment"/>.</returns>
60    public static double Apply(Permutation assignment, Swap2Move move, DoubleMatrix weights, DoubleMatrix distances) {
61      if (move.Index1 == move.Index2) return 0;
62      double moveQuality = 0;
63      int fac1 = move.Index1, fac2 = move.Index2;
64      int loc1 = assignment[fac1], loc2 = assignment[fac2];
65
66      for (int j = 0; j < assignment.Length; j++) {
67        if (j == fac1) {
68          moveQuality += weights[fac1, fac1] * (distances[loc2, loc2] - distances[loc1, loc1]);
69          moveQuality += weights[fac1, fac2] * (distances[loc2, loc1] - distances[loc1, loc2]);
70        } else if (j == fac2) {
71          moveQuality += weights[fac2, fac2] * (distances[loc1, loc1] - distances[loc2, loc2]);
72          moveQuality += weights[fac2, fac1] * (distances[loc1, loc2] - distances[loc2, loc1]);
73        } else {
74          int locJ = assignment[j];
75          moveQuality += weights[fac1, j] * (distances[loc2, locJ] - distances[loc1, locJ]);
76          moveQuality += weights[j, fac1] * (distances[locJ, loc2] - distances[locJ, loc1]);
77          moveQuality += weights[fac2, j] * (distances[loc1, locJ] - distances[loc2, locJ]);
78          moveQuality += weights[j, fac2] * (distances[locJ, loc1] - distances[locJ, loc2]);
79        }
80      }
81      return moveQuality;
82    }
83
84    /// <summary>
85    /// Is able to compute the move qualities faster O(1) in some cases if it knows the quality of
86    /// performing the move <paramref name="move"/> previously. In other cases it performs a
87    /// standard move quality calculation with runtime complexity O(N).
88    /// </summary>
89    /// <remarks>
90    /// The number of cases that the calculation can be performed faster grows with N^2
91    /// while the number of cases which require a larger recalculation grows linearly with N.
92    /// Larger problem instances thus benefit from this faster method to a larger degree.
93    /// </remarks>
94    /// <param name="assignment">The current permutation.</param>
95    /// <param name="move">The current move that is to be evaluated.</param>
96    /// <param name="previousQuality">The quality of that move as evaluated for the previous permutation.</param>
97    /// <param name="weights">The weigths matrix.</param>
98    /// <param name="distances">The distances matrix.</param>
99    /// <param name="lastMove">The move that was applied to transform the permutation from the previous to the current one.</param>
100    /// <returns>The relative change in quality if <paramref name="move"/> was applied to <paramref name="assignment"/>.</returns>
101    public static double Apply(Permutation assignment, Swap2Move move, double previousQuality,
102      DoubleMatrix weights, DoubleMatrix distances, Swap2Move lastMove) {
103      bool overlapsLastMove = move.Index1 == lastMove.Index1
104                           || move.Index2 == lastMove.Index1
105                           || move.Index1 == lastMove.Index2
106                           || move.Index2 == lastMove.Index2;
107
108      if (!overlapsLastMove) {
109        int r = lastMove.Index1, u = move.Index1, s = lastMove.Index2, v = move.Index2;
110        int pR = assignment[lastMove.Index1], pU = assignment[move.Index1], pS = assignment[lastMove.Index2], pV = assignment[move.Index2];
111
112        return previousQuality
113          + (weights[r, u] - weights[r, v] + weights[s, v] - weights[s, u])
114            * (distances[pS, pU] - distances[pS, pV] + distances[pR, pV] - distances[pR, pU])
115          + (weights[u, r] - weights[v, r] + weights[v, s] - weights[u, s])
116            * (distances[pU, pS] - distances[pV, pS] + distances[pV, pR] - distances[pU, pR]);
117      } else {
118        return Apply(assignment, move, weights, distances);
119      }
120    }
121
122    public override IOperation Apply() {
123      Swap2Move move = Swap2MoveParameter.ActualValue;
124      if (move == null) throw new InvalidOperationException("Swap-2 move is not found.");
125      Permutation assignment = PermutationParameter.ActualValue;
126      DoubleMatrix distances = DistancesParameter.ActualValue;
127      DoubleMatrix weights = WeightsParameter.ActualValue;
128
129      double moveQuality = QualityParameter.ActualValue.Value;
130      moveQuality += Apply(assignment, move, weights, distances);
131      MoveQualityParameter.ActualValue = new DoubleValue(moveQuality);
132      return base.Apply();
133    }
134  }
135}
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