#region License Information
/* HeuristicLab
* Copyright (C) 2002-2014 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 .
*/
#endregion
using System;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Encodings.PermutationEncoding;
using HeuristicLab.Optimization.Operators;
namespace HeuristicLab.Problems.TravelingSalesman {
///
/// An operator that performs similarity calculation between two traveling salesman solutions.
///
///
/// The operator calculates the similarity based on the number of edges the two solutions have in common.
///
[Item("TSPSimilarityCalculator", "An operator that performs similarity calculation between two traveling salesman solutions. The operator calculates the similarity based on the number of edges the two solutions have in common.")]
public sealed class TSPSimilarityCalculator : SingleObjectiveSolutionSimilarityCalculator {
private TSPSimilarityCalculator(bool deserializing) : base(deserializing) { }
private TSPSimilarityCalculator(TSPSimilarityCalculator original, Cloner cloner) : base(original, cloner) { }
public TSPSimilarityCalculator() : base() { }
public override IDeepCloneable Clone(Cloner cloner) {
return new TSPSimilarityCalculator(this, cloner);
}
public static double CalculateSimilarity(Permutation left, Permutation right) {
if (left == null || right == null)
throw new ArgumentException("Cannot calculate similarity because one of the provided solutions or both are null.");
if (left.PermutationType != right.PermutationType)
throw new ArgumentException("Cannot calculate similarity because the provided solutions have different types.");
if (left.Length != right.Length)
throw new ArgumentException("Cannot calculate similarity because the provided solutions have different lengths.");
if (object.ReferenceEquals(left, right)) return 1.0;
switch (left.PermutationType) {
case PermutationTypes.Absolute:
return CalculateAbsolute(left, right);
case PermutationTypes.RelativeDirected:
return CalculateRelativeDirected(left, right);
case PermutationTypes.RelativeUndirected:
return CalculateRelativeUndirected(left, right);
default:
throw new InvalidOperationException("unknown permutation type");
}
}
private static double CalculateAbsolute(Permutation left, Permutation right) {
double similarity = 0.0;
for (int i = 0; i < left.Length; i++)
if (left[i] == right[i]) similarity++;
return similarity / left.Length;
}
private static double CalculateRelativeDirected(Permutation left, Permutation right) {
int[] edgesR = CalculateEdgesVector(right);
int[] edgesL = CalculateEdgesVector(left);
double similarity = 0.0;
for (int i = 0; i < left.Length; i++) {
if (edgesL[i] == edgesR[i]) similarity++;
}
return similarity / left.Length;
}
private static double CalculateRelativeUndirected(Permutation left, Permutation right) {
int[] edgesR = CalculateEdgesVector(right);
int[] edgesL = CalculateEdgesVector(left);
double similarity = 0.0;
for (int i = 0; i < left.Length; i++) {
if ((edgesL[i] == edgesR[i]) || (edgesL[edgesR[i]] == i))
similarity++;
}
return similarity / left.Length;
}
private static int[] CalculateEdgesVector(Permutation permutation) {
// transform path representation into adjacency representation
int[] edgesVector = new int[permutation.Length];
for (int i = 0; i < permutation.Length - 1; i++)
edgesVector[permutation[i]] = permutation[i + 1];
edgesVector[permutation[permutation.Length - 1]] = permutation[0];
return edgesVector;
}
public override double CalculateSolutionSimilarity(IScope leftSolution, IScope rightSolution) {
var sol1 = leftSolution.Variables[SolutionVariableName].Value as Permutation;
var sol2 = rightSolution.Variables[SolutionVariableName].Value as Permutation;
return CalculateSimilarity(sol1, sol2);
}
}
}