#region License Information
/* HeuristicLab
* Copyright (C) 2002-2018 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 HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
using System.Collections.Generic;
using HeuristicLab.Data;
using System;
using HeuristicLab.Parameters;
using HeuristicLab.Problems.VehicleRouting.ProblemInstances;
using HeuristicLab.Problems.VehicleRouting.Interfaces;
namespace HeuristicLab.Problems.VehicleRouting.Encodings.Potvin {
[Item("PotvinInsertionBasedCrossover", "The IBX crossover for VRP representations. It is implemented as described in Berger, J and Solois, M and Begin, R (1998). A hybrid genetic algorithm for the vehicle routing problem with time windows. LNCS 1418. Springer, London 114-127.")]
[StorableClass]
public sealed class PotvinInsertionBasedCrossover : PotvinCrossover {
public IValueParameter Length {
get { return (IValueParameter)Parameters["Length"]; }
}
[StorableConstructor]
private PotvinInsertionBasedCrossover(bool deserializing) : base(deserializing) { }
private PotvinInsertionBasedCrossover(PotvinInsertionBasedCrossover original, Cloner cloner)
: base(original, cloner) {
}
public override IDeepCloneable Clone(Cloner cloner) {
return new PotvinInsertionBasedCrossover(this, cloner);
}
public PotvinInsertionBasedCrossover()
: base() {
Parameters.Add(new ValueParameter("Length", "The maximum length of the replaced route.", new IntValue(1)));
}
private static int SelectRandomTourBiasedByLength(IRandom random, PotvinEncoding individual) {
int tourIndex = -1;
double sum = 0.0;
double[] probabilities = new double[individual.Tours.Count];
for (int i = 0; i < individual.Tours.Count; i++) {
probabilities[i] = 1.0 / ((double)individual.Tours[i].Stops.Count / (double)individual.Cities);
sum += probabilities[i];
}
double rand = random.NextDouble() * sum;
double cumulatedProbabilities = 0.0;
int index = 0;
while (tourIndex == -1 && index < probabilities.Length) {
if (cumulatedProbabilities <= rand && rand <= cumulatedProbabilities + probabilities[index])
tourIndex = index;
cumulatedProbabilities += probabilities[index];
index++;
}
return tourIndex;
}
private double CalculateCentroidDistance(Tour t1, Tour t2, IVRPProblemInstance instance) {
double xSum = 0;
double ySum = 0;
double c1X, c1Y, c2X, c2Y;
for (int i = 0; i < t1.Stops.Count; i++) {
xSum += instance.GetCoordinates(t1.Stops[i])[0];
ySum += instance.GetCoordinates(t1.Stops[i])[1];
}
c1X = xSum / t1.Stops.Count;
c1Y = ySum / t1.Stops.Count;
for (int i = 0; i < t2.Stops.Count; i++) {
xSum += instance.GetCoordinates(t2.Stops[i])[0];
ySum += instance.GetCoordinates(t2.Stops[i])[1];
}
c2X = xSum / t1.Stops.Count;
c2Y = ySum / t1.Stops.Count;
return Math.Sqrt(
(c1X - c2X) * (c1X - c2X) +
(c1Y - c2Y) * (c1Y - c2Y));
}
private double CalculateMeanCentroidDistance(Tour t1, IList tours, IVRPProblemInstance instance) {
double sum = 0;
for (int i = 0; i < tours.Count; i++) {
sum += CalculateCentroidDistance(t1, tours[i], instance);
}
return sum / tours.Count;
}
private int SelectCityBiasedByNeighborDistance(IRandom random, Tour tour, IVRPEncoding solution) {
int cityIndex = -1;
double sum = 0.0;
double[] probabilities = new double[tour.Stops.Count];
for (int i = 0; i < tour.Stops.Count; i++) {
int next;
if (i + 1 >= tour.Stops.Count)
next = 0;
else
next = tour.Stops[i + 1];
double distance = ProblemInstance.GetDistance(
tour.Stops[i], next, solution);
int prev;
if (i - 1 < 0)
prev = 0;
else
prev = tour.Stops[i - 1];
distance += ProblemInstance.GetDistance(
tour.Stops[i], prev, solution);
probabilities[i] = distance;
sum += probabilities[i];
}
double rand = random.NextDouble() * sum;
double cumulatedProbabilities = 0.0;
int index = 0;
while (cityIndex == -1 && index < probabilities.Length) {
if (cumulatedProbabilities <= rand && rand <= cumulatedProbabilities + probabilities[index])
cityIndex = index;
cumulatedProbabilities += probabilities[index];
index++;
}
return cityIndex;
}
private bool FindRouteInsertionPlace(
PotvinEncoding individual,
Tour tour,
int city, bool allowInfeasible, out int place) {
place = -1;
if (tour.Stops.Contains(city))
return false;
if (tour.Stops.Count == 0) {
place = 0;
return true;
}
double minDetour = 0;
VRPEvaluation eval = ProblemInstance.EvaluateTour(tour, individual);
bool originalFeasible = ProblemInstance.Feasible(eval);
for (int i = 0; i <= tour.Stops.Count; i++) {
bool feasible;
double detour = ProblemInstance.GetInsertionCosts(eval, individual, city, 0, i, out feasible);
if (feasible || allowInfeasible) {
if (place < 0 || detour < minDetour) {
place = i;
minDetour = detour;
}
}
}
return place >= 0;
}
private ICollection GetUnrouted(PotvinEncoding solution, int cities) {
HashSet undiscovered = new HashSet();
for (int i = 1; i <= cities; i++) {
undiscovered.Add(i);
}
foreach (Tour tour in solution.Tours) {
foreach (int city in tour.Stops)
undiscovered.Remove(city);
}
return undiscovered;
}
protected override PotvinEncoding Crossover(IRandom random, PotvinEncoding parent1, PotvinEncoding parent2) {
PotvinEncoding child = parent1.Clone() as PotvinEncoding;
child.Tours.Clear();
bool allowInfeasible = AllowInfeasibleSolutions.Value.Value;
List R1 = new List();
PotvinEncoding p1Clone = parent1.Clone() as PotvinEncoding;
int length = Math.Min(Length.Value.Value, parent1.Tours.Count) + 1;
int k = 1;
if(length > 1)
k = random.Next(1, length);
for (int i = 0; i < k; i++) {
int index = SelectRandomTourBiasedByLength(random, p1Clone);
R1.Add(p1Clone.Tours[index]);
p1Clone.Tours.RemoveAt(index);
}
foreach (Tour r1 in R1) {
List R2 = new List();
double r = CalculateMeanCentroidDistance(r1, parent2.Tours, ProblemInstance);
foreach (Tour tour in parent2.Tours) {
if (CalculateCentroidDistance(r1, tour, ProblemInstance) <= r) {
R2.AddRange(tour.Stops);
}
}
Tour childTour = new Tour();
child.Tours.Add(childTour);
childTour.Stops.AddRange(r1.Stops);
//DESTROY - remove cities from r1
int removed = 1;
if(r1.Stops.Count > 1)
removed = random.Next(1, r1.Stops.Count + 1);
for (int i = 0; i < removed; i++) {
childTour.Stops.RemoveAt(SelectCityBiasedByNeighborDistance(random, childTour, child));
}
//REPAIR - add cities from R2
int maxCount = 1;
if(R2.Count > 1)
maxCount = random.Next(1, Math.Min(5, R2.Count));
int count = 0;
while (count < maxCount && R2.Count != 0) {
int index = random.Next(R2.Count);
int city = R2[index];
R2.RemoveAt(index);
int place = -1;
bool found = FindRouteInsertionPlace(child, childTour, city, allowInfeasible, out place);
if (found) {
childTour.Stops.Insert(place, city);
if (!Repair(random, child, childTour, ProblemInstance, allowInfeasible)) {
childTour.Stops.RemoveAt(place);
} else {
count++;
}
}
}
Repair(random, child, childTour, ProblemInstance, allowInfeasible);
}
for (int i = 0; i < p1Clone.Tours.Count; i++) {
Tour childTour = p1Clone.Tours[i].Clone() as Tour;
child.Tours.Add(childTour);
Repair(random, child, childTour, ProblemInstance, allowInfeasible);
}
//route unrouted customers
child.Unrouted.AddRange(GetUnrouted(child, ProblemInstance.Cities.Value));
bool success = RouteUnrouted(child, allowInfeasible);
if (success || allowInfeasible)
return child;
else {
if (random.NextDouble() < 0.5)
return parent1.Clone() as PotvinEncoding;
else
return parent2.Clone() as PotvinEncoding;
}
}
}
}