source: branches/PTSP/HeuristicLab.Problems.PTSP/3.3/MoveGenerators/Stochastic25SingleMoveGenerator.cs @ 12797

#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2015 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
 *
 * This file is part of HeuristicLab.
 *
 * HeuristicLab is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
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#endregion

using System;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Optimization;
using HeuristicLab.Parameters;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
using HeuristicLab.Operators;
using HeuristicLab.Encodings.PermutationEncoding;


namespace HeuristicLab.Problems.PTSP {
  [Item("Stochastic25SingleMoveGenerator", "Randomly samples a single from all possible inversion and shift moves (2.5-opt) from a given permutation.")]
  [StorableClass]
  class Stochastic25SingleMoveGenerator : TwoPointFiveMoveGenerator, IStochasticOperator, ISingleMoveGenerator {
    public ILookupParameter<IRandom> RandomParameter {
      get { return (ILookupParameter<IRandom>)Parameters["Random"]; }
    }

    [StorableConstructor]
    protected Stochastic25SingleMoveGenerator(bool deserializing) : base(deserializing) { }
    protected Stochastic25SingleMoveGenerator(Stochastic25SingleMoveGenerator original, Cloner cloner) : base(original, cloner) { }
    public Stochastic25SingleMoveGenerator()
      : base() {
      Parameters.Add(new LookupParameter<IRandom>("Random", "The random number generator."));
    }

    public override IDeepCloneable Clone(Cloner cloner) {
      return new Stochastic25SingleMoveGenerator(this, cloner);
    }

    public static TwoPointFiveMove Apply(Permutation permutation, IRandom random) {
      int length = permutation.Length;
      if (length == 1) throw new ArgumentException("Stochastic25SingleMoveGenerator: There cannot be an inversion move given a permutation of length 1.", "permutation");
      int index1 = random.Next(length - 1);
      int index2 = random.Next(index1 + 1, length);
      if (permutation.PermutationType == PermutationTypes.RelativeUndirected) {
        if (length > 3) {
          while (index2 - index1 >= length - 2)
            index2 = random.Next(index1 + 1, length);
        }
      }
      bool isInvert = random.NextDouble() > 0.5;
      return new TwoPointFiveMove(index1, index2, isInvert);
      
    }

    protected override TwoPointFiveMove[] GenerateMoves(Permutation permutation) {
      IRandom random = RandomParameter.ActualValue;
      return new TwoPointFiveMove[] { Apply(permutation, random) };
    }
  }
}