source: branches/ScatterSearch (trunk integration)/HeuristicLab.Problems.TestFunctions/3.3/PathRelinkers/SingleObjectiveTestFunctionPathRelinker.cs @ 8322

#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2012 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
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * HeuristicLab is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * 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
 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
 */
#endregion

using System;
using System.Collections.Generic;
using System.Linq;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Data;
using HeuristicLab.Encodings.RealVectorEncoding;
using HeuristicLab.Optimization.Operators;
using HeuristicLab.Parameters;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

namespace HeuristicLab.Problems.TestFunctions {
  /// <summary>
  /// An operator that relinks paths between test functions solutions.
  /// </summary>
  /// <remarks>
  /// It is implemented as described in Duarte, A., Martí, R., and Gortazar, F. (2011). Path Relinking for Large Scale Global Optimization. Soft Computing, Vol. 15.
  /// The operator incrementally assimilates the initiating solution into the guiding solution by adapting the solution vector's elements.
  /// </remarks>
  [Item("SingleObjectiveTestFunctionPathRelinker", "An operator that relinks paths between test functions solutions.")]
  [StorableClass]
  public sealed class SingleObjectiveTestFunctionPathRelinker : SingleObjectivePathRelinker {
    #region Parameter properties
    public IValueParameter<IntValue> RelinkingIntensityParameter {
      get { return (IValueParameter<IntValue>)Parameters["RelinkingIntensity"]; }
    }
    #endregion

    #region Properties
    private IntValue RelinkingIntensity {
      get { return RelinkingIntensityParameter.Value; }
    }
    #endregion

    [StorableConstructor]
    private SingleObjectiveTestFunctionPathRelinker(bool deserializing) : base(deserializing) { }
    private SingleObjectiveTestFunctionPathRelinker(SingleObjectiveTestFunctionPathRelinker original, Cloner cloner) : base(original, cloner) { }
    public SingleObjectiveTestFunctionPathRelinker()
      : base() {
      #region Create parameters
      Parameters.Add(new ValueParameter<IntValue>("RelinkingIntensity", "Determines how strong path relinking should be applied.", new IntValue(10)));
      #endregion
    }

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

    public static ItemArray<IItem> Apply(IItem initiator, IItem guide, IntValue k, PercentValue n) {
      if (!(initiator is RealVector) || !(guide is RealVector))
        throw new ArgumentException("Cannot relink path because one of the provided solutions or both have the wrong type.");
      if (n.Value <= 0.0)
        throw new ArgumentException("RelinkingAccuracy must be greater than 0.");

      RealVector v1 = initiator.Clone() as RealVector;
      RealVector v2 = guide as RealVector;

      if (v1.Length != v2.Length)
        throw new ArgumentException("The solutions are of different length.");

      IList<RealVector> solutions = new List<RealVector>();
      for (int i = 0; i < k.Value; i++) {
        RealVector solution = v1.Clone() as RealVector;
        for (int j = 0; j < solution.Length; j++)
          solution[j] = v1[j] + 1 / (k.Value - i) * (v2[j] - v1[j]);
        solutions.Add(solution);
      }

      IList<IItem> selection = new List<IItem>();
      if (solutions.Count > 0) {
        int noSol = (int)(solutions.Count * n.Value);
        if (noSol <= 0) noSol++;
        double stepSize = (double)solutions.Count / (double)noSol;
        for (int i = 0; i < noSol; i++)
          selection.Add(solutions.ElementAt((int)((i + 1) * stepSize - stepSize * 0.5)));
      }

      return new ItemArray<IItem>(selection);
    }

    protected override ItemArray<IItem> Relink(ItemArray<IItem> parents, PercentValue n) {
      if (parents.Length != 2)
        throw new ArgumentException("The number of parents is not equal to 2.");
      return Apply(parents[0], parents[1], RelinkingIntensity, n);
    }
  }
}