source: branches/2457_ExpertSystem/HeuristicLab.Analysis.FitnessLandscape/3.3/DistanceCalculators/PermutationDistanceCalculator.cs @ 17883

#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2016 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.Drawing;
using HEAL.Attic;
using HeuristicLab.Common;
using HeuristicLab.Common.Resources;
using HeuristicLab.Core;
using HeuristicLab.Encodings.PermutationEncoding;

namespace HeuristicLab.Analysis.FitnessLandscape.DistanceCalculators {

  [Item("PermutationDistanceCalculator", "Calculates the distance of two permutations")]
  [StorableType("F2B93749-3059-4D37-91A5-FAE2DC9DB794")]
  public class PermutationDistanceCalculator : NamedItem, IItemDistanceCalculator {

    #region Properties

    public override bool CanChangeName { get { return false; } }
    public override bool CanChangeDescription { get { return false; } }
    public static new Image StaticItemImage { get { return VSImageLibrary.Function; } }

    #endregion

    #region Construction & Cloning

    [StorableConstructor]
    protected PermutationDistanceCalculator(StorableConstructorFlag _) : base(_) { }

    protected PermutationDistanceCalculator(PermutationDistanceCalculator original, Cloner cloner)
      : base(original, cloner) {
    }

    public PermutationDistanceCalculator() {
      name = ItemName;
      description = ItemDescription;
    }

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

    #endregion

    #region IItemDistanceCalculator Members

    public Type ItemType {
      get { return typeof(Permutation); }
    }

    public double Distance(IItem x, IItem y) {
      Permutation a = (Permutation)x;
      Permutation b = (Permutation)y;
      if (a.PermutationType != b.PermutationType)
        throw new InvalidOperationException("Cannot compare two permutations of different type");
      if (a.Length != b.Length)
        throw new InvalidOperationException("Cannot compare vectors of different lengths");
      switch (a.PermutationType) {
        case PermutationTypes.Absolute: return AbsoluteDistance(a, b);
        case PermutationTypes.RelativeDirected: return RelativeDistance(a, b);
        case PermutationTypes.RelativeUndirected: return RelativeDistance(a, b);
        default: throw new NotImplementedException("Unknown permutation type " + a.PermutationType);
      }
    }

    private double AbsoluteDistance(Permutation a, Permutation b) {
      int mismatches = 0;
      for (int i = 0; i < a.Length; i++) {
        if (a[i] != b[i])
          mismatches++;
      }
      return (double)mismatches;
    }

    private double RelativeDistance(Permutation a, Permutation b) {
      HashSet<Point> edges = new HashSet<Point>();
      for (int i = 0; i < a.Length; i++)
        edges.Add(GetEdge(a, i));
      int nCommonEdges = 0;
      for (int i = 0; i < b.Length; i++) {
        if (edges.Contains(GetEdge(b, i)))
          nCommonEdges++;
      }
      return Math.Max(a.Length, b.Length) - nCommonEdges;
    }

    private static Point GetEdge(Permutation a, int index) {
      int start = a[index];
      int end = a[(index + 1) % a.Length];
      switch (a.PermutationType) {
        case PermutationTypes.RelativeDirected: return new Point(start, end);
        case PermutationTypes.RelativeUndirected: return new Point(Math.Min(start, end), Math.Max(start, end));
        default: throw new ArgumentException("cannot derive edge from non-relative permutation type");
      }
    }

    #endregion
  }
}