1  #region License Information


2  /* HeuristicLab


3  * Copyright (C) 20022015 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 


22  using System;


23  using System.Threading;


24  using HeuristicLab.Common;


25  using HeuristicLab.Core;


26  using HeuristicLab.Data;


27  using HeuristicLab.Encodings.PermutationEncoding;


28  using HeuristicLab.Operators;


29  using HeuristicLab.Optimization;


30  using HeuristicLab.Parameters;


31  using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;


32 


33  namespace HeuristicLab.Problems.PTSP {


34  /// <summary>


35  /// An operator that improves probabilistic traveling salesman solutions.


36  /// </summary>


37  /// <remarks>


38  /// The operator tries to improve the probabilistic traveling salesman solution by swapping two randomly chosen edges for a certain number of times.


39  /// </remarks>


40  [Item("PTSP Estimated 2.5 Local Improvement", "An operator that improves probabilistic traveling salesman solutions. The operator tries to improve the probabilistic traveling salesman solution by swapping two randomly chosen edges for a certain number of times.")]


41  [StorableClass]


42  public sealed class PTSPEstimatedTwoPointFiveLocalImprovement : SingleSuccessorOperator, IEstimatedPTSPOperator, ILocalImprovementOperator {


43 


44  public ILookupParameter<IntValue> LocalIterationsParameter {


45  get { return (ILookupParameter<IntValue>)Parameters["LocalIterations"]; }


46  }


47 


48  public IValueLookupParameter<IntValue> MaximumIterationsParameter {


49  get { return (IValueLookupParameter<IntValue>)Parameters["MaximumIterations"]; }


50  }


51 


52  public ILookupParameter<IntValue> EvaluatedSolutionsParameter {


53  get { return (ILookupParameter<IntValue>)Parameters["EvaluatedSolutions"]; }


54  }


55 


56  public ILookupParameter<ResultCollection> ResultsParameter {


57  get { return (ILookupParameter<ResultCollection>)Parameters["Results"]; }


58  }


59 


60  public ILookupParameter<Permutation> PermutationParameter {


61  get { return (ILookupParameter<Permutation>)Parameters["Permutation"]; }


62  }


63 


64  public ILookupParameter<DoubleValue> QualityParameter {


65  get { return (ILookupParameter<DoubleValue>)Parameters["Quality"]; }


66  }


67 


68  public ILookupParameter<BoolValue> MaximizationParameter {


69  get { return (ILookupParameter<BoolValue>)Parameters["Maximization"]; }


70  }


71 


72  public ILookupParameter<DistanceMatrix> DistanceMatrixParameter {


73  get { return (ILookupParameter<DistanceMatrix>)Parameters["DistanceMatrix"]; }


74  }


75 


76  public ILookupParameter<ItemList<BoolArray>> RealizationsParameter {


77  get { return (ILookupParameter<ItemList<BoolArray>>)Parameters["Realizations"]; }


78  }


79 


80  [StorableConstructor]


81  private PTSPEstimatedTwoPointFiveLocalImprovement(bool deserializing) : base(deserializing) { }


82  private PTSPEstimatedTwoPointFiveLocalImprovement(PTSPEstimatedTwoPointFiveLocalImprovement original, Cloner cloner) : base(original, cloner) { }


83  public PTSPEstimatedTwoPointFiveLocalImprovement()


84  : base() {


85  Parameters.Add(new LookupParameter<Permutation>("Permutation", "The solution as permutation."));


86  Parameters.Add(new LookupParameter<IntValue>("LocalIterations", "The number of iterations that have already been performed."));


87  Parameters.Add(new ValueLookupParameter<IntValue>("MaximumIterations", "The maximum amount of iterations that should be performed (note that this operator will abort earlier when a local optimum is reached).", new IntValue(10000)));


88  Parameters.Add(new LookupParameter<IntValue>("EvaluatedSolutions", "The amount of evaluated solutions (here a move is counted only as 4/n evaluated solutions with n being the length of the permutation)."));


89  Parameters.Add(new LookupParameter<ResultCollection>("Results", "The collection where to store results."));


90  Parameters.Add(new LookupParameter<DoubleValue>("Quality", "The quality value of the assignment."));


91  Parameters.Add(new LookupParameter<BoolValue>("Maximization", "True if the problem should be maximized or minimized."));


92  Parameters.Add(new LookupParameter<DistanceMatrix>("DistanceMatrix", "The matrix which contains the distances between the cities."));


93  Parameters.Add(new LookupParameter<ItemList<BoolArray>>("Realizations", "The list of samples drawn from all possible stochastic instances."));


94  }


95 


96  public override IDeepCloneable Clone(Cloner cloner) {


97  return new PTSPEstimatedTwoPointFiveLocalImprovement(this, cloner);


98  }


99 


100  public static void Improve(Permutation assignment, DoubleMatrix distances, DoubleValue quality, IntValue localIterations, IntValue evaluatedSolutions, bool maximization, int maxIterations, ItemList<BoolArray> realizations, CancellationToken cancellation) {


101  var distanceM = (DistanceMatrix)distances;


102  Func<int, int, double> distance = (a, b) => distanceM[a, b];


103  for (var i = localIterations.Value; i < maxIterations; i++) {


104  TwoPointFiveMove bestMove = null;


105  var bestQuality = 0.0; // we have to make an improvement, so 0 is the baseline


106  var evaluations = 0.0;


107  foreach (var move in ExhaustiveTwoPointFiveMoveGenerator.Generate(assignment)) {


108  var moveQuality = PTSPEstimatedTwoPointFiveMoveEvaluator.EvaluateMove(assignment, move, distance, realizations);


109  if (move.IsInvert) evaluations += realizations.Count * 4.0 / (assignment.Length * assignment.Length);


110  else evaluations += realizations.Count * 6.0 / (assignment.Length * assignment.Length);


111  if (maximization && moveQuality > bestQuality


112   !maximization && moveQuality < bestQuality) {


113  bestQuality = moveQuality;


114  bestMove = move;


115  }


116  }


117  evaluatedSolutions.Value += (int)Math.Ceiling(evaluations);


118  if (bestMove == null) break;


119  TwoPointFiveMoveMaker.Apply(assignment, bestMove);


120  quality.Value += bestQuality;


121  localIterations.Value++;


122  cancellation.ThrowIfCancellationRequested();


123  }


124  }


125 


126  public override IOperation Apply() {


127  var maxIterations = MaximumIterationsParameter.ActualValue.Value;


128  var assignment = PermutationParameter.ActualValue;


129  var maximization = MaximizationParameter.ActualValue.Value;


130  var distances = DistanceMatrixParameter.ActualValue;


131  var quality = QualityParameter.ActualValue;


132  var localIterations = LocalIterationsParameter.ActualValue;


133  var evaluations = EvaluatedSolutionsParameter.ActualValue;


134  var realizations = RealizationsParameter.ActualValue;


135  if (localIterations == null) {


136  localIterations = new IntValue(0);


137  LocalIterationsParameter.ActualValue = localIterations;


138  }


139 


140  Improve(assignment, distances, quality, localIterations, evaluations, maximization, maxIterations, realizations, CancellationToken);


141 


142  localIterations.Value = 0;


143  return base.Apply();


144  }


145  }


146  }

