private IRoute Improve(MaxTimeProblem problem,
MaxTimeSolution solution, double max, int currentRouteIdx)
{
// the current route.
IRoute currentRoute = solution.Route(currentRouteIdx);
for (int routeIdx = 0; routeIdx < solution.Count; routeIdx++)
{ // apply the intra-route heurstic between the new and all existing routes.
if (routeIdx != currentRouteIdx &&
this.Overlaps(problem, solution.Route(routeIdx), solution.Route(currentRouteIdx)))
{ // only check routes that overlap.
if (this.ImproveInterRoute(problem, solution, routeIdx, currentRouteIdx, max))
{ // an improvement was found, again to the intra operators.
if (!solution.IsValid())
{
throw new Exception();
}
solution[currentRouteIdx] = this.ImproveIntraRoute(problem, currentRoute, solution[currentRouteIdx]);
solution[routeIdx] = this.ImproveIntraRoute(problem, solution.Route(routeIdx), solution[routeIdx]);
// recalculate weights.
solution[currentRouteIdx] = problem.Time(solution.Route(currentRouteIdx));
solution[routeIdx] = problem.Time(solution.Route(routeIdx));
}
}
}
return(solution.Route(solution.Count - 1));
}
/// <summary>
/// Creates a new TSP problem.
/// </summary>
/// <param name="vrp"></param>
public TSPProblem(MaxTimeProblem vrp)
{
this.Size = vrp.Size;
this.Symmetric = false;
this.Euclidean = false;
this.First = 0;
this.Last = 0;
this.WeightMatrix = vrp.WeightMatrix;
}
/// <summary>
/// Creates a new TSP problem.
/// </summary>
/// <param name="vrp"></param>
public TSPProblem(MaxTimeProblem vrp)
{
this.Size = vrp.Size;
this.Symmetric = false;
this.Euclidean = false;
this.First = 0;
this.Last = 0;
this.WeightMatrix = vrp.WeightMatrix;
}
/// <summary>
/// Selects a new seed customer.
/// </summary>
/// <param name="problem"></param>
/// <param name="calculator"></param>
/// <param name="solution"></param>
/// <param name="customers"></param>
/// <returns></returns>
private int SelectSeed(MaxTimeProblem problem, MaxTimeCalculator calculator,
MaxTimeSolution solution, List <int> customers)
{
int selected_customer = -1;
double max_distance = double.MaxValue;
foreach (int customer_to_check in customers)
{
SortedDictionary <double, List <int> > neighbours = new SortedDictionary <double, List <int> >();
for (int idx = 0; idx < customers.Count; idx++)
{
int customer = customers[idx];
if (customer != customer_to_check)
{
double weight = problem.WeightMatrix[customer_to_check][customer] +
problem.WeightMatrix[customer_to_check][customer];
List <int> customers_list = null;
if (!neighbours.TryGetValue(weight, out customers_list))
{
customers_list = new List <int>();
neighbours.Add(weight, customers_list);
}
customers_list.Add(customer);
}
}
double nearest_neighbour_average = 0;
int neighbour_count = 20;
int neighbour_counted = 0;
foreach (KeyValuePair <double, List <int> > pair in neighbours)
{
foreach (int customer in pair.Value)
{
if (neighbour_counted < neighbour_count)
{
neighbour_counted++;
nearest_neighbour_average = nearest_neighbour_average +
pair.Key;
}
else
{
break;
}
}
}
if (max_distance > nearest_neighbour_average)
{
max_distance = nearest_neighbour_average;
selected_customer = customer_to_check;
}
}
return(selected_customer);
}
/// <summary>
/// Tries to improve the existing routes by re-inserting a customer from one route into another.
/// </summary>
/// <param name="problem"></param>
/// <param name="solution"></param>
/// <param name="route1_idx"></param>
/// <param name="route2_idx"></param>
/// <param name="max"></param>
/// <returns></returns>
public bool Improve(MaxTimeProblem problem, MaxTimeSolution solution,
int route1_idx, int route2_idx, double max)
{
if (this.RelocateFromTo(problem, solution, route1_idx, route2_idx, max))
{
return true;
}
if (this.RelocateFromTo(problem, solution, route2_idx, route1_idx, max))
{
return true;
}
return false;
}
/// <summary>
/// Tries to improve the existing routes by re-inserting a customer from one route into another.
/// </summary>
/// <param name="problem"></param>
/// <param name="solution"></param>
/// <param name="route1_idx"></param>
/// <param name="route2_idx"></param>
/// <param name="max"></param>
/// <returns></returns>
public bool Improve(MaxTimeProblem problem, MaxTimeSolution solution,
int route1_idx, int route2_idx, double max)
{
if (this.RelocateFromTo(problem, solution, route1_idx, route2_idx, max))
{
return(true);
}
if (this.RelocateFromTo(problem, solution, route2_idx, route1_idx, max))
{
return(true);
}
return(false);
}
/// <summary>
/// Selects a new seed customer.
/// </summary>
/// <param name="problem"></param>
/// <param name="calculator"></param>
/// <param name="solution"></param>
/// <param name="customers"></param>
/// <returns></returns>
private int SelectSeed(MaxTimeProblem problem, MaxTimeCalculator calculator,
MaxTimeSolution solution, List <int> customers)
{ // select the customer farthest from the depot.
int selectedCustomer = -1;
double maxDistance = double.MinValue;
foreach (int customerToCheck in customers)
{
double distance = problem.WeightMatrix[0][customerToCheck] +
problem.WeightMatrix[customerToCheck][0];
if (distance > maxDistance)
{
maxDistance = distance;
selectedCustomer = customerToCheck;
}
}
return(selectedCustomer);
}
/// <summary>
/// Tries a relocation of the customers in route1 to route2.
/// </summary>
/// <param name="problem"></param>
/// <param name="solution"></param>
/// <param name="route1_idx"></param>
/// <param name="route2_idx"></param>
/// <param name="max"></param>
/// <returns></returns>
private bool RelocateFromTo(MaxTimeProblem problem, MaxTimeSolution solution,
int route1_idx, int route2_idx, double max)
{
int previous = -1;
int current = -1;
IRoute route1 = solution.Route(route1_idx);
IRoute route2 = solution.Route(route2_idx);
double route2_weight = solution[route2_idx];
foreach (int next in route1)
{
if (previous >= 0 && current >= 0)
{ // consider the next customer.
int count_before1 = route1.Count;
int count_before2 = route2.Count;
// string route1_string = route1.ToString();
// string route2_string = route2.ToString();
if (this.ConsiderCustomer(problem, route2, previous, current, next, route2_weight, max))
{
route1.ReplaceEdgeFrom(previous, next);
int count_after = route1.Count + route2.Count;
if ((count_before1 + count_before2) != count_after)
{
throw new Exception();
}
return(true);
}
}
previous = current;
current = next;
}
return(false);
}
/// <summary>
/// Executes a solver procedure.
/// </summary>
/// <param name="problem"></param>
/// <returns></returns>
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
_customers = problem.Customers;
//float[] solutions = OsmSharp.Math.VRP.Core.BestPlacement.CheapestInsertionHelper.CalculateBestValues(
// problem, _customers);
generations = 0;
_max_generations = 10000000;
// calculate one tsp solution.
//Tools.Math.TSP.ISolver tsp_solver = new OsmSharp.Math.TSP.EdgeAssemblyGenetic.EdgeAssemblyCrossOverSolver(_population, _stagnation,
// new OsmSharp.Math.TSP.Genetic.Solver.Operations.Generation._3OptGenerationOperation(),
// new OsmSharp.Math.TSP.Genetic.Solver.Operations.CrossOver.EdgeAssemblyCrossover(30,
// OsmSharp.Math.TSP.Genetic.Solver.Operations.CrossOver.EdgeAssemblyCrossover.EdgeAssemblyCrossoverSelectionStrategyEnum.SingleRandom,
// true));
//IRoute tsp_solution = tsp_solver.Solve(new OsmSharp.Routing.VRP.NoDepot.MaxTime.TSPPlacement.TSPProblem(
// problem));
// initialize the generation.
IGenerationOperation <MaxTimeSolution, MaxTimeProblem, Fitness> generation =
//new SolverGenerationOperation(new TSPPlacement.TSPPlacementSolver<ResolvedType>(
// this.Router, this.Max, this.DeliveryTime, tsp_solution));
new OsmSharp.Routing.VRP.NoDepot.MaxTime.Genetic.Generation.RandomBestPlacement();
//new SolverGenerationOperation(new CheapestInsertionSolverWithImprovements<ResolvedType>(
// this.Router, this.Max, this.DeliveryTime, 5, 0.1f, true, 0.1f, false, 1f, null, null));
//new SolverGenerationOperation(new CheapestInsertionSolverWithImprovements<ResolvedType>(
// this.Router, this.Max, this.DeliveryTime, 5, 0.1f, true, 0.1f, true, 1f));
// initialize the crossover.
ICrossOverOperation <MaxTimeSolution, MaxTimeProblem, Fitness> cross_over =
new OsmSharp.Routing.VRP.NoDepot.MaxTime.Genetic.CrossOver.RouteExchangeOperation();
// initialize the mutation.
//IMutationOperation<MaxTimeSolution, MaxTimeProblem, Fitness> mutation =
// new VehicleMutation();
List <IMutationOperation <MaxTimeSolution, MaxTimeProblem, Fitness> > mutators =
new List <IMutationOperation <MaxTimeSolution, MaxTimeProblem, Fitness> >();
mutators.Add(new VehicleMutation());
//mutators.Add(new ThreeOptMutation());
//mutators.Add(new RedivideRouteMutation());
mutators.Add(new RoutePartExchangeMutation());
if (_probabilities == null)
{
_probabilities = new List <double>();
_probabilities.Add(0.2);
_probabilities.Add(0.6);
_probabilities.Add(0.2);
}
CombinedMutation <MaxTimeSolution, MaxTimeProblem, Fitness> mutation = new CombinedMutation <MaxTimeSolution, MaxTimeProblem, Fitness>(
StaticRandomGenerator.Get(),
mutators,
_probabilities);
SolverSettings settings = new SolverSettings(_stagnation, _population, _max_generations,
_elitism_percentage, _cross_percentage, _mutation_percentage);
MaxTimeProblem genetic_problem = problem;// new MaxTimeProblem(max, problem, solutions);
Solver <MaxTimeSolution, MaxTimeProblem, Fitness> solver =
new Solver <MaxTimeSolution, MaxTimeProblem, Fitness>(genetic_problem, settings,
new TournamentBasedSelector <MaxTimeSolution, MaxTimeProblem, Fitness>(5, 0.5),
mutation, //new ThreeOptMutation(),
cross_over, // new RouteExchangeOperation(), //new RouteExchangeOperation(), //new RouteExchangeAndVehicleOperation(), // Order1CrossoverOperation()
generation, //new RandomBestPlacement(),//new RandomGeneration(), //new RandomBestPlacement(),
new FitnessCalculator());
solver.NewFittest += new Solver <MaxTimeSolution, MaxTimeProblem, Fitness> .NewFittestDelegate(solver_NewFittest);
//solver.NewGeneration += new Solver<MaxTimeSolution, Problem, Fitness>.NewGenerationDelegate(solver_NewGeneration);
Individual <MaxTimeSolution, MaxTimeProblem, Fitness> solution = solver.Start(null);
//this.solver_NewFittest(solution);
MaxTimeSolution routes = solution.Genomes;
long ticks_after = DateTime.Now.Ticks;
StringBuilder sizes = new StringBuilder();
foreach (int size in routes.Sizes)
{
sizes.Append(size);
sizes.Append(" ");
}
StringBuilder weights = new StringBuilder();
foreach (double weight in solution.Fitness.Weights)
{
weights.Append(weight.ToString(CultureInfo.InvariantCulture));
weights.Append(" ");
}
return(routes);
}
/// <summary>
/// Applies inter-improvements by exchanging customers.
/// </summary>
/// <param name="problem"></param>
/// <param name="solution"></param>
/// <param name="route1_idx"></param>
/// <param name="route2_idx"></param>
/// <param name="max"></param>
/// <returns></returns>
public bool Improve(MaxTimeProblem problem, MaxTimeSolution solution,
int route1_idx, int route2_idx, double max)
{
IRoute route1 = solution.Route(route1_idx);
IRoute route2 = solution.Route(route2_idx);
double total_before = problem.Time(solution.Route(route1_idx)) +
problem.Time(solution.Route(route2_idx));
double route1_size = solution[route1_idx];
double route2_size = solution[route2_idx];
// this heuristic removes a customer1 from route1 and a customer2 from route2 and inserts the customers again
// but swappes them; customer1 in route2 and customer2 in route1.
int previous_customer1 = -1;
//if (route1.IsRound)
//{
// previous_customer1= route1.Last; // set the previous customer.
//}
foreach (int customer1 in route1)
{ // loop over all customers in route1.
if (previous_customer1 >= 0)
{ // the previous customer is set.
int next_customer1 = route1.GetNeigbours(customer1)[0];
if (next_customer1 < 0)
{
continue;
}
int previous_customer2 = -1;
//if (route2.IsRound)
//{
// previous_customer2 = route2.Last; // set the previous customer.
//}
foreach (int customer2 in route2)
{ // loop over all customers in route2.
int next_customer2 = route2.GetNeigbours(customer2)[0];
if (previous_customer2 >= 0 && next_customer2 >= 0)
{ // the previous customer is set.
float weight1 = (float)problem.WeightMatrix[previous_customer1][customer1] +
(float)problem.WeightMatrix[customer1][next_customer1];
float weight2 = (float)problem.WeightMatrix[previous_customer2][customer2] +
(float)problem.WeightMatrix[customer2][next_customer2];
float weight1_after = (float)problem.WeightMatrix[previous_customer1][customer2] +
(float)problem.WeightMatrix[customer2][next_customer1];
float weight2_after = (float)problem.WeightMatrix[previous_customer2][customer1] +
(float)problem.WeightMatrix[customer1][next_customer2];
double difference = (weight1_after + weight2_after) - (weight1 + weight2);
if (difference < -0.01)
{ // the old weights are bigger!
// check if the new routes are bigger than max.
if (route1_size + (weight1_after - weight1) <= max &&
route2_size + (weight2_after - weight1) <= max)
{ // the exchange can happen, both routes stay within bound!
// exchange customer.
int count_before = route1.Count + route2.Count;
//route1.Remove(customer1);
//route2.Remove(customer2);
if (previous_customer1 == next_customer2)
{
throw new Exception();
}
//route1.InsertAfter(previous_customer1, customer2);
//route2.InsertAfter(previous_customer2, customer1);
route1.ReplaceEdgeFrom(previous_customer1, customer2);
route1.ReplaceEdgeFrom(customer2, next_customer1);
route2.ReplaceEdgeFrom(previous_customer2, customer1);
route2.ReplaceEdgeFrom(customer1, next_customer2);
int count_after = route1.Count + route2.Count;
if (count_before != count_after)
{
throw new Exception();
}
double total_after = problem.Time(solution.Route(route1_idx)) +
problem.Time(solution.Route(route2_idx));
if (total_after >= total_before)
{
throw new Exception("this is not an improvement!");
}
return(true);
}
}
}
previous_customer2 = customer2; // set the previous customer.
}
}
previous_customer1 = customer1; // set the previous customer.
}
return(false);
}
/// <summary>
/// Apply some improvements between the given routes and returns the resulting weight.
/// </summary>
/// <param name="problem"></param>
/// <param name="solution"></param>
/// <param name="route1Idx"></param>
/// <param name="route2Idx"></param>
/// <param name="max"></param>
/// <returns></returns>
private bool ImproveInterRoute(MaxTimeProblem problem, MaxTimeSolution solution,
int route1Idx, int route2Idx, double max)
{
// get the routes.
IRoute route1 = solution.Route(route1Idx);
IRoute route2 = solution.Route(route2Idx);
int countBefore = route1.Count + route2.Count;
// loop over all improvement operations.
bool globalImprovement = false;
foreach (IInterImprovement improvementOperation in _inter_improvements)
{ // try the current improvement operations.
bool improvement = true;
while (improvement)
{ // keep looping when there is improvement.
improvement = false;
double totalBefore = problem.Time(solution.Route(route1Idx)) +
problem.Time(solution.Route(route2Idx));
if (improvementOperation.Improve(problem, solution, route1Idx, route2Idx, max))
{ // there was an improvement.
improvement = true;
globalImprovement = true;
// check if the route is valid.
if (!route1.IsValid())
{
throw new Exception();
}
if (!route2.IsValid())
{
throw new Exception();
}
int countAfter = route1.Count + route2.Count;
if (countBefore != countAfter)
{
throw new Exception();
}
double totalAfter = problem.Time(solution.Route(route1Idx)) +
problem.Time(solution.Route(route2Idx));
if (totalAfter >= totalBefore)
{
throw new Exception("this is not an improvement!");
}
OsmSharp.Logging.Log.TraceEvent("OsmSharp.Routing.VRP.NoDepot.MaxTime.VNS.GuidedVNS", TraceEventType.Information,
"Inter-improvement found {0}<->{1}: {2} ({3}->{4})",
route1Idx, route2Idx, improvementOperation.Name, totalBefore, totalAfter);
// recalculate weights.
solution[route1Idx] = problem.Time(solution.Route(route1Idx));
solution[route2Idx] = problem.Time(solution.Route(route2Idx));
//break;
}
else if (!improvementOperation.IsSymmetric &&
improvementOperation.Improve(problem, solution, route2Idx, route1Idx, max))
{ // also do the improvement the other way around when not symmetric.
improvement = true;
globalImprovement = true;
// check if the route is valid.
if (!route1.IsValid())
{
throw new Exception();
}
if (!route2.IsValid())
{
throw new Exception();
}
int countAfter = route1.Count + route2.Count;
if (countBefore != countAfter)
{
throw new Exception();
}
double totalAfter = problem.Time(solution.Route(route1Idx)) +
problem.Time(solution.Route(route2Idx));
if (totalAfter >= totalBefore)
{
throw new Exception("this is not an improvement!");
}
OsmSharp.Logging.Log.TraceEvent("OsmSharp.Routing.VRP.NoDepot.MaxTime.VNS.GuidedVNS", TraceEventType.Information,
"Inter-improvement found {0}<->{1}: {2} ({3}->{4})",
route2Idx, route1Idx, improvementOperation.Name, totalBefore, totalAfter);
// recalculate weights.
solution[route1Idx] = problem.Time(solution.Route(route1Idx));
solution[route2Idx] = problem.Time(solution.Route(route2Idx));
//break;
}
}
}
return globalImprovement;
}
/// <summary>
/// Executes a solver procedure.
/// </summary>
/// <param name="problem"></param>
/// <returns></returns>
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
// create the solution.
var solution = new MaxTimeSolution(problem.Size);
// keep placing customer until none are left.
var customers = new List <int>(problem.Customers);
customers.RemoveAt(0);
double max = problem.Max.Value - (problem.Max.Value * _deltaPercentage);
// keep a list of cheapest insertions.
IInsertionCosts costs = new BinaryHeapInsertionCosts();
double percentage = _thresholdPercentage;
while (customers.Count > 0)
{
//// try and distribute the remaining customers if there are only a few left.
//if (customers.Count < problem.Size * percentage)
//{
// bool succes = true;
// while (succes && customers.Count > 0)
// {
// succes = false;
// CheapestInsertionResult best = new CheapestInsertionResult();
// best.Increase = float.MaxValue;
// int best_idx = -1;
// for (int route_idx = 0; route_idx < solution.Count; route_idx++)
// {
// IRoute route = solution.Route(route_idx);
// CheapestInsertionResult result =
// CheapestInsertionHelper.CalculateBestPlacement(problem, route, customers);
// if (best.Increase > result.Increase)
// {
// best = result;
// best_idx = route_idx;
// }
// }
// IRoute best_route = solution.Route(best_idx);
// double route_time = problem.Time(best_route);
// if (route_time + best.Increase < max)
// { // insert the customer.
// best_route.InsertAfter(best.CustomerBefore, best.Customer);
// customers.Remove(best.Customer);
// this.Improve(problem, solution, max, best_idx);
// succes = true;
// }
// }
//}
// select a customer using some heuristic.
int customer = this.SelectSeed(problem, problem.MaxTimeCalculator, solution, customers);
customers.Remove(customer);
// start a route r.
IRoute currentRoute = solution.Add(customer);
solution[solution.Count - 1] = 0;
while (customers.Count > 0)
{
// calculate the best placement.
CheapestInsertionResult result;
if (_useSeedCost)
{ // use the seed cost; the cost to the seed customer.
result = CheapestInsertionHelper.CalculateBestPlacement(problem, currentRoute, customers,
customer, 0.7);
// calculate the 'real' increase.
result.Increase = (problem.WeightMatrix[result.CustomerBefore][result.Customer] +
problem.WeightMatrix[result.Customer][result.CustomerAfter]) -
problem.WeightMatrix[result.CustomerBefore][result.CustomerAfter];
}
else
{ // just use cheapest insertion.
result = CheapestInsertionHelper.CalculateBestPlacement(problem, currentRoute, customers, costs);
}
// calculate the new weight.
solution[solution.Count - 1] = problem.Time(solution.Route(solution.Count - 1));
double potentialWeight = problem.MaxTimeCalculator.CalculateOneRouteIncrease(solution[solution.Count - 1],
result.Increase);
// cram as many customers into one route as possible.
if (potentialWeight < max)
{
// insert the customer, it is
customers.Remove(result.Customer);
currentRoute.InsertAfter(result.CustomerBefore, result.Customer);
// free some memory in the costs list.
costs.Remove(result.CustomerBefore, result.CustomerAfter);
// update the cost of the route.
solution[solution.Count - 1] = potentialWeight;
// improve if needed.
if (((problem.Size - customers.Count) % _k) == 0)
{ // an improvement is decided.
// apply the inter-route improvements.
var copy = (solution.Clone() as MaxTimeSolution);
int countBefore = solution.Route(solution.Count - 1).Count;
solution[solution.Count - 1] = this.ImproveIntraRoute(problem,
solution.Route(solution.Count - 1), solution[solution.Count - 1]);
if (!solution.IsValid())
{
throw new Exception();
}
int countAfter = solution.Route(solution.Count - 1).Count;
if (countAfter != countBefore)
{
throw new Exception();
}
// also to the inter-improvements.
currentRoute = this.Improve(problem, solution, max, solution.Count - 1);
}
}
else
{// ok we are done!
this.Improve(problem, solution, max, solution.Count - 1);
// break the route.
break;
}
}
}
// remove empty routes.
for (int routeIdx = solution.Count - 1; routeIdx >= 0; routeIdx--)
{
if (solution.Route(routeIdx).IsEmpty)
{
solution.Remove(routeIdx);
}
}
return(solution);
}
/// <summary>
/// Try and merge route2 into route1.
/// </summary>
/// <param name="problem"></param>
/// <param name="solution"></param>
/// <param name="route1_idx"></param>
/// <param name="route2_idx"></param>
/// <param name="max"></param>
/// <returns></returns>
private MergeResult TryMerge(MaxTimeProblem problem, MaxTimeSolution solution,
int route1_idx, int route2_idx, double max)
{
// get the route weights.
double route1_weight = solution[route1_idx];
double route2_weight = solution[route2_idx];
// creates a result.
MergeResult result = new MergeResult();
result.Weight = double.MaxValue;
// get the two routes.
IRoute route1 = solution.Route(route1_idx);
IRoute route2 = solution.Route(route2_idx);
// just first do the case where both routes are of zero length.
if (route1.Count == 1 && route2.Count == 1)
{ // calculate the increase when joining the two points.
foreach (int customer1 in route1)
{
foreach (int customer2 in route2)
{
double difference = problem.WeightMatrix[customer1][customer2] +
problem.WeightMatrix[customer2][customer1];
double new_route_weight = route1_weight + difference + route2_weight;
if (new_route_weight < max)
{
result.Weight = difference;
result.RouteSourceId = route2_idx;
result.RouteTargetId = route1_idx;
result.CustomerSourceSource = customer2;
result.CustomerSourceTarget = customer2;
result.CustomerTargetSource = customer1;
return result;
}
}
}
}
foreach (Edge route1_edge in route1.Edges())
{ // loop over all route1 edges.
// calculate weight of the current edge.
double route1_edge_weight = problem.WeightMatrix[route1_edge.From][route1_edge.To];
double route1_edge_without = route1_weight - route1_edge_weight;
if (route2.Count == 1)
{ // there is only one customer.
foreach (int customer2 in route2)
{
//// calculate weight of the current edge.
//double route2_edge_weight = problem.WeightMatrix[route2_edge.From][route2_edge.To];
//double route2_edge_without = route2_weight - route2_edge_weight;
double new_edges_weight = problem.WeightMatrix[route1_edge.From][customer2] +
problem.WeightMatrix[customer2][route1_edge.To];
double difference = problem.WeightDifferenceAfterMerge(solution,
new_edges_weight - (route1_edge_weight));
// check if the max bound is not violated.
double new_route_weight = route1_edge_without + difference + route2_weight; // the customer remain the same.
if (new_route_weight < max)
{
// the difference is smaller than the current result.
if (difference < result.Weight)
{
result.Weight = difference;
result.RouteSourceId = route2_idx;
result.RouteTargetId = route1_idx;
result.CustomerSourceSource = customer2;
result.CustomerSourceTarget = customer2;
result.CustomerTargetSource = route1_edge.From;
}
}
}
}
else
{ // there is at least one edge.
foreach (Edge route2_edge in route2.Edges())
{ // loop over all route2 edges.
// calculate weight of the current edge.
double route2_edge_weight = problem.WeightMatrix[route2_edge.From][route2_edge.To];
double route2_edge_without = route2_weight - route2_edge_weight;
double new_edges_weight = problem.WeightMatrix[route1_edge.From][route2_edge.To] +
problem.WeightMatrix[route2_edge.From][route1_edge.To];
double difference = problem.WeightDifferenceAfterMerge(solution,
new_edges_weight - (route1_edge_weight + route2_edge_weight));
// check if the max bound is not violated.
double new_route_weight = route1_edge_weight + route2_edge_without + new_edges_weight; // the customer remain the same.
if (new_route_weight < max)
{
// the difference is smaller than the current result.
if (difference < result.Weight)
{
result.Weight = difference;
result.RouteSourceId = route2_idx;
result.RouteTargetId = route1_idx;
result.CustomerSourceSource = route2_edge.To;
result.CustomerSourceTarget = route2_edge.From;
result.CustomerTargetSource = route1_edge.From;
}
}
}
}
}
return result;
}
/// <summary>
/// Selects a new seed customer.
/// </summary>
/// <param name="problem"></param>
/// <param name="calculator"></param>
/// <param name="solution"></param>
/// <param name="customers"></param>
/// <returns></returns>
private int SelectSeed(MaxTimeProblem problem, MaxTimeCalculator calculator,
MaxTimeSolution solution, List<int> customers)
{
int selected_customer = -1;
double max_distance = double.MaxValue;
foreach (int customer_to_check in customers)
{
SortedDictionary<double, List<int>> neighbours = new SortedDictionary<double, List<int>>();
for (int idx = 0; idx < customers.Count; idx++)
{
int customer = customers[idx];
if (customer != customer_to_check)
{
double weight = problem.WeightMatrix[customer_to_check][customer] +
problem.WeightMatrix[customer_to_check][customer];
List<int> customers_list = null;
if (!neighbours.TryGetValue(weight, out customers_list))
{
customers_list = new List<int>();
neighbours.Add(weight, customers_list);
}
customers_list.Add(customer);
}
}
double nearest_neighbour_average = 0;
int neighbour_count = 20;
int neighbour_counted = 0;
foreach (KeyValuePair<double, List<int>> pair in neighbours)
{
foreach (int customer in pair.Value)
{
if (neighbour_counted < neighbour_count)
{
neighbour_counted++;
nearest_neighbour_average = nearest_neighbour_average +
pair.Key;
}
else
{
break;
}
}
}
if (max_distance > nearest_neighbour_average)
{
max_distance = nearest_neighbour_average;
selected_customer = customer_to_check;
}
}
return selected_customer;
}
private IRoute Improve(MaxTimeProblem problem,
MaxTimeSolution solution, double max, int current_route_idx)
{
// the current route.
IRoute current_route = solution.Route(current_route_idx);
for (int route_idx = 0; route_idx < solution.Count; route_idx++)
{ // apply the intra-route heurstic between the new and all existing routes.
if (route_idx != current_route_idx &&
this.Overlaps(problem, solution.Route(route_idx), solution.Route(current_route_idx)))
{ // only check routes that overlap.
if (this.ImproveInterRoute(problem, solution, route_idx, current_route_idx, max))
{ // an improvement was found, again to the intra operators.
if (!solution.IsValid())
{
throw new Exception();
}
solution[current_route_idx] = this.ImproveIntraRoute(problem, current_route, solution[current_route_idx]);
solution[route_idx] = this.ImproveIntraRoute(problem, solution.Route(route_idx), solution[route_idx]);
// recalculate weights.
solution[current_route_idx] = problem.Time(solution.Route(current_route_idx));
solution[route_idx] = problem.Time(solution.Route(route_idx));
}
}
}
return solution.Route(solution.Count - 1);
}
/// <summary>
/// Executes a solver procedure.
/// </summary>
/// <param name="problem"></param>
/// <returns></returns>
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
// create the solution.
MaxTimeSolution solution = new MaxTimeSolution(problem.Size, true);
// keep placing customer until none are left.
List<int> customers = new List<int>(problem.Customers);
double max = problem.Max.Value - (problem.Max.Value * _delta_percentage);
// keep a list of cheapest insertions.
IInsertionCosts costs = new BinaryHeapInsertionCosts();
double percentage = _threshold_percentage;
while (customers.Count > 0)
{
// try and distribute the remaining customers if there are only a few left.
if (customers.Count < problem.Size * percentage)
{
bool succes = true;
while (succes && customers.Count > 0)
{
succes = false;
CheapestInsertionResult best = new CheapestInsertionResult();
best.Increase = float.MaxValue;
int best_idx = -1;
for (int route_idx = 0; route_idx < solution.Count; route_idx++)
{
IRoute route = solution.Route(route_idx);
CheapestInsertionResult result =
CheapestInsertionHelper.CalculateBestPlacement(problem, route, customers);
if (best.Increase > result.Increase)
{
best = result;
best_idx = route_idx;
}
}
IRoute best_route = solution.Route(best_idx);
double route_time = problem.Time(best_route);
if (route_time + best.Increase < max)
{ // insert the customer.
best_route.InsertAfter(best.CustomerBefore, best.Customer);
customers.Remove(best.Customer);
this.Improve(problem, solution, max, best_idx);
succes = true;
}
}
}
// select a customer using some heuristic.
if (customers.Count > 0)
{
// select a customer using some heuristic.
int customer = -1;
if (_use_seed)
{ // use a seeding heuristic.
customer = this.SelectSeed(problem, problem.MaxTimeCalculator, solution, customers);
}
else
{ // just select a random customer.
customer = customers[Math.Random.StaticRandomGenerator.Get().Generate(customers.Count)];
}
customers.Remove(customer);
// start a route r.
IRoute current_route = solution.Add(customer);
solution[solution.Count - 1] = 0;
while (customers.Count > 0)
{
//OsmSharp.IO.Output.OutputStreamHost.WriteLine("{0}/{1} placed!",
// customers.Count, problem.Size);
// calculate the best placement.
CheapestInsertionResult result;
if (_use_seed_cost)
{ // use the seed cost; the cost to the seed customer.
result = CheapestInsertionHelper.CalculateBestPlacement(problem, current_route, customers,
customer, _lambda);
// calculate the 'real' increase.
result.Increase = (problem.WeightMatrix[result.CustomerBefore][result.Customer] +
problem.WeightMatrix[result.Customer][result.CustomerAfter]) -
problem.WeightMatrix[result.CustomerBefore][result.CustomerAfter];
}
else
{ // just use cheapest insertion.
result = CheapestInsertionHelper.CalculateBestPlacement(problem, current_route, customers, costs);
}
// calculate the new weight.
solution[solution.Count - 1] = problem.Time(solution.Route(solution.Count - 1));
double potential_weight = problem.MaxTimeCalculator.CalculateOneRouteIncrease(solution[solution.Count - 1],
result.Increase);
// cram as many customers into one route as possible.
if (potential_weight < max)
{
// insert the customer, it is
customers.Remove(result.Customer);
current_route.InsertAfter(result.CustomerBefore, result.Customer);
// free some memory in the costs list.
costs.Remove(result.CustomerBefore, result.CustomerAfter);
// update the cost of the route.
solution[solution.Count - 1] = potential_weight;
// improve if needed.
if (((problem.Size - customers.Count) % _k) == 0)
{ // an improvement is descided.
// apply the inter-route improvements.
int count_before = solution.Route(solution.Count - 1).Count;
solution[solution.Count - 1] = this.ImproveIntraRoute(problem,
current_route, solution[solution.Count - 1]);
if (!solution.IsValid())
{
throw new Exception();
}
int count_after = solution.Route(solution.Count - 1).Count;
// also to the inter-improvements.
current_route = this.Improve(problem, solution, max, solution.Count - 1);
}
}
else
{// ok we are done!
this.Improve(problem, solution, max, solution.Count - 1);
// break the route.
break;
}
}
//else
//{// ok we are done!
// solution[solution.Count - 1] = this.ImproveIntraRoute(problem,
// current_route, solution[solution.Count - 1]);
// if (!solution.IsValid())
// {
// throw new Exception();
// }
// int count_after = solution.Route(solution.Count - 1).Count;
// this.Improve(problem, solution, max, solution.Count - 1);
// // break the route.
// break;
//}
}
}
// remove empty routes.
for (int route_idx = solution.Count - 1; route_idx >= 0; route_idx--)
{
if (solution.Route(route_idx).IsEmpty)
{
solution.Remove(route_idx);
}
}
return solution;
}
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
MaxTimeCalculator calculator = new MaxTimeCalculator(
problem);
// generate a ATSP solution.
IRoute tsp_solution = _tsp_solution;
if (tsp_solution == null)
{
tsp_solution = _tsp_solver.Solve(new TSPProblem(problem));
}
// generate subtours from this solution.
MaxTimeSolution solution = new MaxTimeSolution(problem.Size, true);
// select a random start point.
int start = OsmSharp.Math.Random.StaticRandomGenerator.Get().Generate(problem.Size);
// start the first tour.
int placed = 0;
int previous = -1;
// place the first customer.
double weight = 0;
double total_weight = 0;
IRoute route = solution.Add(start);
previous = start;
while (placed < problem.Size)
{
// get the next customer from the tsp solution.
int next = tsp_solution.GetNeigbours(previous)[0];
// get the weight to the current start.
double weight_to_next = problem.WeightMatrix[previous][next];
double weight_to_start = problem.WeightMatrix[next][start];
total_weight = calculator.CalculateOneRouteIncrease(
weight, weight_to_next + weight_to_start);
weight = calculator.CalculateOneRouteIncrease(
weight, weight_to_next);
if (total_weight > problem.Max.Value)
{ // start a new route.
route = solution.Add(next);
weight = 0;
}
else
{ // just insert the next customer.
route.InsertAfter(previous, next);
//route.InsertAfterAndRemove(previous, next, -1);
}
// set the previous.
previous = next;
placed++;
}
if (!solution.IsValid())
{
throw new Exception();
}
StringBuilder builder = new StringBuilder();
builder.Append("[");
total_weight = 0;
for (int idx = 0; idx < solution.Count; idx++)
{
//IRoute route = routes.Route(idx);
route = solution.Route(idx);
weight = calculator.CalculateOneRoute(route);
builder.Append(" ");
builder.Append(weight);
builder.Append(" ");
total_weight = total_weight + weight;
}
builder.Append("]");
builder.Append(total_weight);
builder.Append(": ");
builder.Append(calculator.Calculate(solution));
OsmSharp.Logging.Log.TraceEvent("TSPPlacementSolver", TraceEventType.Information, builder.ToString());
return solution;
}
/// <summary>
/// Tries to relocate customers using the source the same as the CrossExchange but places customers using cheapest insertion.
/// </summary>
/// <param name="problem"></param>
/// <param name="solution"></param>
/// <param name="route1_idx"></param>
/// <param name="route2_idx"></param>
/// <param name="max"></param>
/// <returns></returns>
public bool Improve(MaxTimeProblem problem, MaxTimeSolution solution,
int route1_idx, int route2_idx, double max)
{
int max_window = 5;
IRoute route1 = solution.Route(route1_idx);
IRoute route2 = solution.Route(route2_idx);
double total_before = problem.Time(solution.Route(route1_idx)) +
problem.Time(solution.Route(route2_idx));
int route1_customers = route1.Count;
int route2_customers = route2.Count;
double[] route1_cumul = problem.TimeCumul(route1);
double[] route2_cumul = problem.TimeCumul(route2);
// build all edge weights.
List<Edge> route1_edges = new List<Edge>(route1.Edges());
List<Edge> route2_edges = new List<Edge>(route2.Edges());
double[] route1_weights = new double[route1_edges.Count];
for (int idx = 0; idx < route1_edges.Count; idx++)
{
Edge edge = route1_edges[idx];
route1_weights[idx] = problem.WeightMatrix[edge.From][edge.To];
}
double[] route2_weights = new double[route2_edges.Count];
for (int idx = 0; idx < route2_edges.Count; idx++)
{
Edge edge = route2_edges[idx];
route2_weights[idx] = problem.WeightMatrix[edge.From][edge.To];
}
List<EdgePair> route2_pairs = new List<EdgePair>();
for (int i_idx = 0; i_idx < route2_edges.Count - 2; i_idx++)
{
Edge i = route2_edges[i_idx];
double i_weight = route2_weights[i_idx];
double weight_before_i = route2_cumul[i_idx];
int k_idx_max = route2_edges.Count;
if (k_idx_max > i_idx + 2 + max_window)
{
k_idx_max = i_idx + 2 + max_window;
}
for (int k_idx = i_idx + 2; k_idx < k_idx_max; k_idx++)
{
Edge k = route2_edges[k_idx];
double k_weight = route2_weights[k_idx];
double weight_after_k = route2_cumul[route2_cumul.Length - 1] - route2_cumul[k_idx + 1];
double weight_between_route = route2_cumul[k_idx] - route2_cumul[i_idx + 1];
route2_pairs.Add(new EdgePair()
{
First = i,
FirstWeight = i_weight,
Second = k,
SecondWeight = k_weight,
Between = new List<int>(route2.Between(i.To, k.From)),
WeightTotal = i_weight + k_weight,
WeightAfter = weight_after_k,
WeightBefore = weight_before_i,
WeightBetween = weight_between_route,
CustomersBetween = k_idx - i_idx
});
}
}
// try to relocate all and find best pair.
double route1_weight = route1_cumul[route1_cumul.Length - 1];
EdgePair best = null;
CheapestInsertionResult best_result = new CheapestInsertionResult();
double best_extra = double.MaxValue;
foreach (EdgePair pair2 in route2_pairs)
{
// calculate cheapest insertion.
CheapestInsertionResult result =
CheapestInsertionHelper.CalculateBestPlacement(problem, route1,
pair2.First.To, pair2.Second.From);
double extra_route2 = problem.WeightMatrix[pair2.First.From][pair2.Second.To];
// check if the result has a net-decrease.
if (result.Increase + extra_route2 < pair2.WeightTotal - 0.01)
{ // there is a net decrease.
// calculate the real increase.
double new_weight = problem.Time(route1_weight + result.Increase + pair2.WeightBetween, route1_customers +
pair2.CustomersBetween);
// check the max.
if (new_weight < max && new_weight < best_extra)
{ // the route is smaller than max.
best_extra = new_weight;
best_result = result;
best = pair2;
}
}
}
if (best != null)
{
if (route2.Last == best.Second.To)
{
//throw new Exception();
}
route2.ReplaceEdgeFrom(best.First.From, best.Second.To);
int previous = best_result.CustomerBefore;
foreach (int customer in best.Between)
{
route1.ReplaceEdgeFrom(previous, customer);
previous = customer;
}
route1.ReplaceEdgeFrom(previous, best_result.CustomerAfter);
// check validity.
if (!route2.IsValid())
{
throw new Exception();
}
if (!route1.IsValid())
{
throw new Exception();
}
if (route1.Count + route2.Count != route1_customers + route2_customers)
{
throw new Exception();
}
double total_after = problem.Time(solution.Route(route1_idx)) +
problem.Time(solution.Route(route2_idx));
if (total_after >= total_before)
{
throw new Exception("this is not an improvement!");
}
return true;
}
return false;
}
/// <summary>
/// Calculates a solution.
/// </summary>
/// <param name="problem"></param>
/// <returns></returns>
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
// create the calculator.
MaxTimeCalculator calculator = new MaxTimeCalculator(problem);
// create the solution.
MaxTimeSolution solution = new MaxTimeSolution(problem.Size, true);
double max = problem.Max.Value;
// keep placing customer until none are left.
List <int> customers = new List <int>(problem.Customers);
// create n routes.
for (int customer = 0; customer < customers.Count; customer++)
{
solution.Add(customer);
solution[solution.Count - 1] = calculator.CalculateOneRouteIncrease(
0, 0);
}
// creates a result.
MergeResult result = new MergeResult();
result.Weight = double.MaxValue;
// loop over all route pairs and merge the smallest merge.
while (result != null)
{ // keep looping until there is no result anymore.
result = new MergeResult();
result.Weight = double.MaxValue;
for (int route1_idx = 1; route1_idx < solution.Count; route1_idx++)
{ // keep looping over all routes.
for (int route2_idx = 0; route2_idx < solution.Count; route2_idx++)
{ // keep looping over all routes.
if (route1_idx == route2_idx)
{ // only consider different routes.
break;
}
// calculate the merge result.
MergeResult current_result = this.TryMerge(problem, solution,
route1_idx, route2_idx, problem.Max.Value);
// evaluate the current result.
if (current_result != null && current_result.Weight < result.Weight)
{ // current result is best.
result = current_result;
}
}
}
// evaluate the result.
if (result.Weight < double.MaxValue)
{ // there is a result; apply it!
IRoute source = solution.Route(result.RouteSourceId);
IRoute target = solution.Route(result.RouteTargetId);
//string source_string = source.ToString();
//string target_string = target.ToString();
if (target.Count > 1 && target.First == target.GetNeigbours(result.CustomerTargetSource)[0])
{
//throw new Exception();
}
// create an enumeration of all customers of source in the correct order.
IEnumerable <int> source_between = new List <int>(
source.Between(result.CustomerSourceSource, result.CustomerSourceTarget));
// insert after the complete source.
int previous = result.CustomerTargetSource;
int next = target.GetNeigbours(result.CustomerTargetSource)[0];
foreach (int source_customer in source_between)
{
// insert.
target.ReplaceEdgeFrom(previous, source_customer);
previous = source_customer; // update previous.
}
target.ReplaceEdgeFrom(previous, next);
// remove the source route.
solution.Remove(result.RouteSourceId);
solution.RemoveWeight(result.RouteTargetId);
// calculate the weight of the new route.
solution[result.RouteTargetId] = solution[result.RouteTargetId] + result.Weight +
solution[result.RouteSourceId];
if (!solution.IsValid())
{
throw new Exception();
}
}
else
{ // set the result null.
result = null;
}
}
return(solution);
}
/// <summary>
/// Executes a solver procedure.
/// </summary>
/// <param name="problem"></param>
/// <returns></returns>
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
// create the solution.
var solution = new MaxTimeSolution(problem.Size);
// keep placing customer until none are left.
var customers = new List<int>(problem.Customers);
customers.RemoveAt(0);
double max = problem.Max.Value - (problem.Max.Value * _deltaPercentage);
// keep a list of cheapest insertions.
IInsertionCosts costs = new BinaryHeapInsertionCosts();
// double percentage = _thresholdPercentage;
while (customers.Count > 0)
{
//// try and distribute the remaining customers if there are only a few left.
//if (customers.Count < problem.Size * percentage)
//{
// bool succes = true;
// while (succes && customers.Count > 0)
// {
// succes = false;
// CheapestInsertionResult best = new CheapestInsertionResult();
// best.Increase = float.MaxValue;
// int best_idx = -1;
// for (int route_idx = 0; route_idx < solution.Count; route_idx++)
// {
// IRoute route = solution.Route(route_idx);
// CheapestInsertionResult result =
// CheapestInsertionHelper.CalculateBestPlacement(problem, route, customers);
// if (best.Increase > result.Increase)
// {
// best = result;
// best_idx = route_idx;
// }
// }
// IRoute best_route = solution.Route(best_idx);
// double route_time = problem.Time(best_route);
// if (route_time + best.Increase < max)
// { // insert the customer.
// best_route.InsertAfter(best.CustomerBefore, best.Customer);
// customers.Remove(best.Customer);
// this.Improve(problem, solution, max, best_idx);
// succes = true;
// }
// }
//}
// select a customer using some heuristic.
int customer = this.SelectSeed(problem, problem.MaxTimeCalculator, solution, customers);
customers.Remove(customer);
// start a route r.
IRoute currentRoute = solution.Add(customer);
solution[solution.Count - 1] = 0;
while (customers.Count > 0)
{
// calculate the best placement.
CheapestInsertionResult result;
if (_useSeedCost)
{ // use the seed cost; the cost to the seed customer.
result = CheapestInsertionHelper.CalculateBestPlacement(problem, currentRoute, customers,
customer, 0.7);
// calculate the 'real' increase.
result.Increase = (problem.WeightMatrix[result.CustomerBefore][result.Customer] +
problem.WeightMatrix[result.Customer][result.CustomerAfter]) -
problem.WeightMatrix[result.CustomerBefore][result.CustomerAfter];
}
else
{ // just use cheapest insertion.
result = CheapestInsertionHelper.CalculateBestPlacement(problem, currentRoute, customers, costs);
}
// calculate the new weight.
solution[solution.Count - 1] = problem.Time(solution.Route(solution.Count - 1));
double potentialWeight = problem.MaxTimeCalculator.CalculateOneRouteIncrease(solution[solution.Count - 1],
result.Increase);
// cram as many customers into one route as possible.
if (potentialWeight < max)
{
// insert the customer, it is
customers.Remove(result.Customer);
currentRoute.InsertAfter(result.CustomerBefore, result.Customer);
// free some memory in the costs list.
costs.Remove(result.CustomerBefore, result.CustomerAfter);
// update the cost of the route.
solution[solution.Count - 1] = potentialWeight;
// improve if needed.
if (((problem.Size - customers.Count) % _k) == 0)
{ // an improvement is decided.
// apply the inter-route improvements.
// var copy = (solution.Clone() as MaxTimeSolution);
int countBefore = solution.Route(solution.Count - 1).Count;
solution[solution.Count - 1] = this.ImproveIntraRoute(problem,
solution.Route(solution.Count - 1), solution[solution.Count - 1]);
if (!solution.IsValid())
{
throw new Exception();
}
int countAfter = solution.Route(solution.Count - 1).Count;
if (countAfter != countBefore)
{
throw new Exception();
}
// also to the inter-improvements.
currentRoute = this.Improve(problem, solution, max, solution.Count - 1);
}
}
else
{// ok we are done!
this.Improve(problem, solution, max, solution.Count - 1);
// break the route.
break;
}
}
}
// remove empty routes.
for (int routeIdx = solution.Count - 1; routeIdx >= 0; routeIdx--)
{
if (solution.Route(routeIdx).IsEmpty)
{
solution.Remove(routeIdx);
}
}
return solution;
}
///// <summary>
///// Apply some improvements between the given routes and returns the resulting weight.
///// </summary>
///// <param name="problem"></param>
///// <param name="route"></param>
///// <returns></returns>
//private bool ImproveInterRoute(MaxTimeProblem problem, MaxTimeSolution solution, int route1_idx, int route2_idx, double max)
//{
// // get the routes.
// IRoute route1 = solution.Route(route1_idx);
// IRoute route2 = solution.Route(route2_idx);
// int count_before = route1.Count + route2.Count;
// // get the weights.
// double route1_weight = solution[route1_idx];
// double route2_weight = solution[route2_idx];
// // loop over all improvement operations.
// bool global_improvement = false;
// foreach (IInterImprovement improvement_operation in _inter_improvements)
// { // try the current improvement operations.
// bool improvement = true;
// while (improvement)
// { // keep looping when there is improvement.
// improvement = false;
// if (improvement_operation.Improve(problem, solution, route1_idx, route2_idx, max))
// { // there was an improvement.
// improvement = true;
// global_improvement = true;
// OsmSharp.Tools.Output.OutputStreamHost.WriteLine("Inter-improvement found {0}<->{1}: {2}",
// route1_idx, route2_idx, improvement_operation.Name);
// // check if the route is valid.
// if (!route1.IsValid())
// {
// throw new Exception();
// }
// if (!route2.IsValid())
// {
// throw new Exception();
// }
// int count_after = route1.Count + route2.Count;
// if (count_before != count_after)
// {
// throw new Exception();
// }
// // recalculate weights.
// solution[route1_idx] = problem.Time(solution.Route(route1_idx));
// solution[route2_idx] = problem.Time(solution.Route(route2_idx));
// //break;
// }
// }
// }
// return global_improvement;
//}
/// <summary>
/// Apply some improvements between the given routes and returns the resulting weight.
/// </summary>
/// <param name="problem"></param>
/// <param name="solution"></param>
/// <param name="route1_idx"></param>
/// <param name="route2_idx"></param>
/// <param name="max"></param>
/// <returns></returns>
private bool ImproveInterRoute(MaxTimeProblem problem, MaxTimeSolution solution,
int route1_idx, int route2_idx, double max)
{
// get the routes.
IRoute route1 = solution.Route(route1_idx);
IRoute route2 = solution.Route(route2_idx);
int count_before = route1.Count + route2.Count;
//// get the weights.
//double route1_weight = solution[route1_idx];
//double route2_weight = solution[route2_idx];
// loop over all improvement operations.
bool global_improvement = false;
foreach (IInterImprovement improvement_operation in _inter_improvements)
{ // try the current improvement operations.
bool improvement = true;
while (improvement)
{ // keep looping when there is improvement.
improvement = false;
double total_before = problem.Time(solution.Route(route1_idx)) +
problem.Time(solution.Route(route2_idx));
if (improvement_operation.Improve(problem, solution, route1_idx, route2_idx, max))
{ // there was an improvement.
improvement = true;
global_improvement = true;
// check if the route is valid.
if (!route1.IsValid())
{
throw new Exception();
}
if (!route2.IsValid())
{
throw new Exception();
}
int count_after = route1.Count + route2.Count;
if (count_before != count_after)
{
throw new Exception();
}
double total_after = problem.Time(solution.Route(route1_idx)) +
problem.Time(solution.Route(route2_idx));
if (total_after >= total_before)
{
throw new Exception("this is not an improvement!");
}
OsmSharp.Tools.Output.OutputStreamHost.WriteLine("Inter-improvement found {0}<->{1}: {2} ({3}->{4})",
route1_idx, route2_idx, improvement_operation.Name, total_before, total_after);
// recalculate weights.
solution[route1_idx] = problem.Time(solution.Route(route1_idx));
solution[route2_idx] = problem.Time(solution.Route(route2_idx));
//break;
}
else if (!improvement_operation.IsSymmetric &&
improvement_operation.Improve(problem, solution, route2_idx, route1_idx, max))
{ // also do the improvement the other way around when not symmetric.
improvement = true;
global_improvement = true;
// check if the route is valid.
if (!route1.IsValid())
{
throw new Exception();
}
if (!route2.IsValid())
{
throw new Exception();
}
int count_after = route1.Count + route2.Count;
if (count_before != count_after)
{
throw new Exception();
}
double total_after = problem.Time(solution.Route(route1_idx)) +
problem.Time(solution.Route(route2_idx));
if (total_after >= total_before)
{
throw new Exception("this is not an improvement!");
}
OsmSharp.Tools.Output.OutputStreamHost.WriteLine("Inter-improvement found {0}<->{1}: {2} ({3}->{4})",
route2_idx, route1_idx, improvement_operation.Name, total_before, total_after);
// recalculate weights.
solution[route1_idx] = problem.Time(solution.Route(route1_idx));
solution[route2_idx] = problem.Time(solution.Route(route2_idx));
//break;
}
}
}
return global_improvement;
}
/// <summary>
/// Executes a solver procedure.
/// </summary>
/// <param name="problem"></param>
/// <returns></returns>
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
// create the solution.
MaxTimeSolution solution = new MaxTimeSolution(problem.Size, true);
// keep placing customer until none are left.
List <int> customers = new List <int>(problem.Customers);
double max = problem.Max.Value - (problem.Max.Value * _delta_percentage);
// keep a list of cheapest insertions.
IInsertionCosts costs = new BinaryHeapInsertionCosts();
double percentage = _threshold_percentage;
while (customers.Count > 0)
{
// try and distribute the remaining customers if there are only a few left.
if (customers.Count < problem.Size * percentage)
{
bool succes = true;
while (succes && customers.Count > 0)
{
succes = false;
CheapestInsertionResult best = new CheapestInsertionResult();
best.Increase = float.MaxValue;
int best_idx = -1;
for (int route_idx = 0; route_idx < solution.Count; route_idx++)
{
IRoute route = solution.Route(route_idx);
CheapestInsertionResult result =
CheapestInsertionHelper.CalculateBestPlacement(problem, route, customers);
if (best.Increase > result.Increase)
{
best = result;
best_idx = route_idx;
}
}
IRoute best_route = solution.Route(best_idx);
double route_time = problem.Time(best_route);
if (route_time + best.Increase < max)
{ // insert the customer.
best_route.InsertAfter(best.CustomerBefore, best.Customer);
customers.Remove(best.Customer);
this.Improve(problem, solution, max, best_idx);
succes = true;
}
}
}
// select a customer using some heuristic.
if (customers.Count > 0)
{
// select a customer using some heuristic.
int customer = -1;
if (_use_seed)
{ // use a seeding heuristic.
customer = this.SelectSeed(problem, problem.MaxTimeCalculator, solution, customers);
}
else
{ // just select a random customer.
customer = customers[Math.Random.StaticRandomGenerator.Get().Generate(customers.Count)];
}
customers.Remove(customer);
// start a route r.
IRoute current_route = solution.Add(customer);
solution[solution.Count - 1] = 0;
while (customers.Count > 0)
{
//OsmSharp.IO.Output.OutputStreamHost.WriteLine("{0}/{1} placed!",
// customers.Count, problem.Size);
// calculate the best placement.
CheapestInsertionResult result;
if (_use_seed_cost)
{ // use the seed cost; the cost to the seed customer.
result = CheapestInsertionHelper.CalculateBestPlacement(problem, current_route, customers,
customer, _lambda);
// calculate the 'real' increase.
result.Increase = (problem.WeightMatrix[result.CustomerBefore][result.Customer] +
problem.WeightMatrix[result.Customer][result.CustomerAfter]) -
problem.WeightMatrix[result.CustomerBefore][result.CustomerAfter];
}
else
{ // just use cheapest insertion.
result = CheapestInsertionHelper.CalculateBestPlacement(problem, current_route, customers, costs);
}
// calculate the new weight.
solution[solution.Count - 1] = problem.Time(solution.Route(solution.Count - 1));
double potential_weight = problem.MaxTimeCalculator.CalculateOneRouteIncrease(solution[solution.Count - 1],
result.Increase);
// cram as many customers into one route as possible.
if (potential_weight < max)
{
// insert the customer, it is
customers.Remove(result.Customer);
current_route.InsertAfter(result.CustomerBefore, result.Customer);
// free some memory in the costs list.
costs.Remove(result.CustomerBefore, result.CustomerAfter);
// update the cost of the route.
solution[solution.Count - 1] = potential_weight;
// improve if needed.
if (((problem.Size - customers.Count) % _k) == 0)
{ // an improvement is descided.
// apply the inter-route improvements.
int count_before = solution.Route(solution.Count - 1).Count;
solution[solution.Count - 1] = this.ImproveIntraRoute(problem,
current_route, solution[solution.Count - 1]);
if (!solution.IsValid())
{
throw new Exception();
}
int count_after = solution.Route(solution.Count - 1).Count;
// also to the inter-improvements.
current_route = this.Improve(problem, solution, max, solution.Count - 1);
}
}
else
{// ok we are done!
this.Improve(problem, solution, max, solution.Count - 1);
// break the route.
break;
}
}
//else
//{// ok we are done!
// solution[solution.Count - 1] = this.ImproveIntraRoute(problem,
// current_route, solution[solution.Count - 1]);
// if (!solution.IsValid())
// {
// throw new Exception();
// }
// int count_after = solution.Route(solution.Count - 1).Count;
// this.Improve(problem, solution, max, solution.Count - 1);
// // break the route.
// break;
//}
}
}
// remove empty routes.
for (int route_idx = solution.Count - 1; route_idx >= 0; route_idx--)
{
if (solution.Route(route_idx).IsEmpty)
{
solution.Remove(route_idx);
}
}
return(solution);
}
/// <summary>
/// Calculates a solution.
/// </summary>
/// <param name="problem"></param>
/// <returns></returns>
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
// create the calculator.
MaxTimeCalculator calculator = new MaxTimeCalculator(problem);
// create the solution.
MaxTimeSolution solution = new MaxTimeSolution(problem.Size, true);
double max = problem.Max.Value;
// keep placing customer until none are left.
List<int> customers = new List<int>(problem.Customers);
// create n routes.
for (int customer = 0; customer < customers.Count; customer++)
{
solution.Add(customer);
solution[solution.Count - 1] = calculator.CalculateOneRouteIncrease(
0, 0);
}
// creates a result.
MergeResult result = new MergeResult();
result.Weight = double.MaxValue;
// loop over all route pairs and merge the smallest merge.
while (result != null)
{ // keep looping until there is no result anymore.
result = new MergeResult();
result.Weight = double.MaxValue;
for (int route1_idx = 1; route1_idx < solution.Count; route1_idx++)
{ // keep looping over all routes.
for (int route2_idx = 0; route2_idx < solution.Count; route2_idx++)
{ // keep looping over all routes.
if (route1_idx == route2_idx)
{ // only consider different routes.
break;
}
// calculate the merge result.
MergeResult current_result = this.TryMerge(problem, solution,
route1_idx, route2_idx, problem.Max.Value);
// evaluate the current result.
if (current_result != null && current_result.Weight < result.Weight)
{ // current result is best.
result = current_result;
}
}
}
// evaluate the result.
if (result.Weight < double.MaxValue)
{ // there is a result; apply it!
IRoute source = solution.Route(result.RouteSourceId);
IRoute target = solution.Route(result.RouteTargetId);
//string source_string = source.ToString();
//string target_string = target.ToString();
if (target.Count > 1 && target.First == target.GetNeigbours(result.CustomerTargetSource)[0])
{
//throw new Exception();
}
// create an enumeration of all customers of source in the correct order.
IEnumerable<int> source_between = new List<int>(
source.Between(result.CustomerSourceSource, result.CustomerSourceTarget));
// insert after the complete source.
int previous = result.CustomerTargetSource;
int next = target.GetNeigbours(result.CustomerTargetSource)[0];
foreach (int source_customer in source_between)
{
// insert.
target.ReplaceEdgeFrom(previous, source_customer);
previous = source_customer; // update previous.
}
target.ReplaceEdgeFrom(previous, next);
// remove the source route.
solution.Remove(result.RouteSourceId);
solution.RemoveWeight(result.RouteTargetId);
// calculate the weight of the new route.
solution[result.RouteTargetId] = solution[result.RouteTargetId] + result.Weight +
solution[result.RouteSourceId];
if (!solution.IsValid())
{
throw new Exception();
}
}
else
{ // set the result null.
result = null;
}
}
return solution;
}
/// <summary>
/// Try and merge route2 into route1.
/// </summary>
/// <param name="problem"></param>
/// <param name="solution"></param>
/// <param name="route1_idx"></param>
/// <param name="route2_idx"></param>
/// <param name="max"></param>
/// <returns></returns>
private MergeResult TryMerge(MaxTimeProblem problem, MaxTimeSolution solution,
int route1_idx, int route2_idx, double max)
{
// get the route weights.
double route1_weight = solution[route1_idx];
double route2_weight = solution[route2_idx];
// creates a result.
MergeResult result = new MergeResult();
result.Weight = double.MaxValue;
// get the two routes.
IRoute route1 = solution.Route(route1_idx);
IRoute route2 = solution.Route(route2_idx);
// just first do the case where both routes are of zero length.
if (route1.Count == 1 && route2.Count == 1)
{ // calculate the increase when joining the two points.
foreach (int customer1 in route1)
{
foreach (int customer2 in route2)
{
double difference = problem.WeightMatrix[customer1][customer2] +
problem.WeightMatrix[customer2][customer1];
double new_route_weight = route1_weight + difference + route2_weight;
if (new_route_weight < max)
{
result.Weight = difference;
result.RouteSourceId = route2_idx;
result.RouteTargetId = route1_idx;
result.CustomerSourceSource = customer2;
result.CustomerSourceTarget = customer2;
result.CustomerTargetSource = customer1;
return(result);
}
}
}
}
foreach (Edge route1_edge in route1.Edges())
{ // loop over all route1 edges.
// calculate weight of the current edge.
double route1_edge_weight = problem.WeightMatrix[route1_edge.From][route1_edge.To];
double route1_edge_without = route1_weight - route1_edge_weight;
if (route2.Count == 1)
{ // there is only one customer.
foreach (int customer2 in route2)
{
//// calculate weight of the current edge.
//double route2_edge_weight = problem.WeightMatrix[route2_edge.From][route2_edge.To];
//double route2_edge_without = route2_weight - route2_edge_weight;
double new_edges_weight = problem.WeightMatrix[route1_edge.From][customer2] +
problem.WeightMatrix[customer2][route1_edge.To];
double difference = problem.WeightDifferenceAfterMerge(solution,
new_edges_weight - (route1_edge_weight));
// check if the max bound is not violated.
double new_route_weight = route1_edge_without + difference + route2_weight; // the customer remain the same.
if (new_route_weight < max)
{
// the difference is smaller than the current result.
if (difference < result.Weight)
{
result.Weight = difference;
result.RouteSourceId = route2_idx;
result.RouteTargetId = route1_idx;
result.CustomerSourceSource = customer2;
result.CustomerSourceTarget = customer2;
result.CustomerTargetSource = route1_edge.From;
}
}
}
}
else
{ // there is at least one edge.
foreach (Edge route2_edge in route2.Edges())
{ // loop over all route2 edges.
// calculate weight of the current edge.
double route2_edge_weight = problem.WeightMatrix[route2_edge.From][route2_edge.To];
double route2_edge_without = route2_weight - route2_edge_weight;
double new_edges_weight = problem.WeightMatrix[route1_edge.From][route2_edge.To] +
problem.WeightMatrix[route2_edge.From][route1_edge.To];
double difference = problem.WeightDifferenceAfterMerge(solution,
new_edges_weight - (route1_edge_weight + route2_edge_weight));
// check if the max bound is not violated.
double new_route_weight = route1_edge_weight + route2_edge_without + new_edges_weight; // the customer remain the same.
if (new_route_weight < max)
{
// the difference is smaller than the current result.
if (difference < result.Weight)
{
result.Weight = difference;
result.RouteSourceId = route2_idx;
result.RouteTargetId = route1_idx;
result.CustomerSourceSource = route2_edge.To;
result.CustomerSourceTarget = route2_edge.From;
result.CustomerTargetSource = route1_edge.From;
}
}
}
}
}
return(result);
}
/// <summary>
/// Selects a new seed customer.
/// </summary>
/// <param name="problem"></param>
/// <param name="calculator"></param>
/// <param name="solution"></param>
/// <param name="customers"></param>
/// <returns></returns>
private int SelectSeed(MaxTimeProblem problem, MaxTimeCalculator calculator,
MaxTimeSolution solution, List<int> customers)
{
// select the customer farthest from the depot.
int selectedCustomer = -1;
double maxDistance = double.MinValue;
foreach (int customerToCheck in customers)
{
double distance = problem.WeightMatrix[0][customerToCheck] +
problem.WeightMatrix[customerToCheck][0];
if (distance > maxDistance)
{
maxDistance = distance;
selectedCustomer = customerToCheck;
}
}
return selectedCustomer;
}
/// <summary>
/// Executes a solver procedure.
/// </summary>
/// <param name="problem"></param>
/// <returns></returns>
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
// create the calculator.
MaxTimeCalculator calculator = new MaxTimeCalculator(problem);
// create the solution.
MaxTimeSolution solution = new MaxTimeSolution(problem.Size, true);
// keep placing customer until none are left.
List<int> customers = new List<int>(problem.Customers);
while (customers.Count > 0)
{
// select a customer using some heuristic.
int customer_idx = OsmSharp.Tools.Math.Random.StaticRandomGenerator.Get().Generate(customers.Count);
int customer = customers[customer_idx];
customers.Remove(customer);
// start a route r.
double current_route_weight = 0;
IRoute current_route = solution.Add(customer);
//Console.WriteLine("Starting new route with {0}", customer);
while (customers.Count > 0)
{
// calculate the best placement.
CheapestInsertionResult result =
CheapestInsertionHelper.CalculateBestPlacement(problem, current_route, customers);
// calculate the new weight.
double potential_weight = calculator.CalculateOneRouteIncrease(current_route_weight, result.Increase);
// cram as many customers into one route as possible.
if (potential_weight < problem.Max.Value)
{
// insert the customer, it is
customers.Remove(result.Customer);
//current_route.InsertAfterAndRemove(result.CustomerBefore, result.Customer, result.CustomerAfter);
current_route.InsertAfter(result.CustomerBefore, result.Customer);
current_route_weight = potential_weight;
//// improve if needed.
////if (improvement_probalitity > OsmSharp.Tools.Math.Random.StaticRandomGenerator.Get().Generate(1))
//if (((problem.Size - customers.Count) % _k) == 0)
//{ // an improvement is descided.
// current_route_weight = this.ImproveIntraRoute(problem,
// current_route, current_route_weight);
//}
}
else
{// ok we are done!
//// apply the intra-route heuristics.
//for (int route_idx = 0; route_idx < solution.Count - 1; route_idx++)
//{ // apply the intra-route heurstic between the new and all existing routes.
// this.ImproveInterRoute(problem, solution.Route(route_idx), current_route);
//}
//// apply the inter-route heuristics.
//for (int route_idx = 0; route_idx < solution.Count; route_idx++)
//{ // apply heurstic for each route.
// IRoute route = solution.Route(route_idx);
// this.ImproveIntraRoute(problem, current_route, current_route_weight);
//}
// break the route.
break;
}
}
}
return solution;
}
/// <summary>
/// Applies inter-improvements by exchanging customers.
/// </summary>
/// <param name="problem"></param>
/// <param name="solution"></param>
/// <param name="route1_idx"></param>
/// <param name="route2_idx"></param>
/// <param name="max"></param>
/// <returns></returns>
public bool Improve(MaxTimeProblem problem, MaxTimeSolution solution,
int route1_idx, int route2_idx, double max)
{
IRoute route1 = solution.Route(route1_idx);
IRoute route2 = solution.Route(route2_idx);
double total_before = problem.Time(solution.Route(route1_idx)) +
problem.Time(solution.Route(route2_idx));
double route1_size = solution[route1_idx];
double route2_size = solution[route2_idx];
// this heuristic removes a customer1 from route1 and a customer2 from route2 and inserts the customers again
// but swappes them; customer1 in route2 and customer2 in route1.
int previous_customer1 = -1;
//if (route1.IsRound)
//{
// previous_customer1= route1.Last; // set the previous customer.
//}
foreach (int customer1 in route1)
{ // loop over all customers in route1.
if (previous_customer1 >= 0)
{ // the previous customer is set.
int next_customer1 = route1.GetNeigbours(customer1)[0];
if (next_customer1 < 0)
{
continue;
}
int previous_customer2 = -1;
//if (route2.IsRound)
//{
// previous_customer2 = route2.Last; // set the previous customer.
//}
foreach (int customer2 in route2)
{ // loop over all customers in route2.
int next_customer2 = route2.GetNeigbours(customer2)[0];
if (previous_customer2 >= 0 && next_customer2 >= 0)
{ // the previous customer is set.
float weight1 = (float)problem.WeightMatrix[previous_customer1][customer1] +
(float)problem.WeightMatrix[customer1][next_customer1];
float weight2 = (float)problem.WeightMatrix[previous_customer2][customer2] +
(float)problem.WeightMatrix[customer2][next_customer2];
float weight1_after = (float)problem.WeightMatrix[previous_customer1][customer2] +
(float)problem.WeightMatrix[customer2][next_customer1];
float weight2_after = (float)problem.WeightMatrix[previous_customer2][customer1] +
(float)problem.WeightMatrix[customer1][next_customer2];
double difference = (weight1_after + weight2_after) - (weight1 + weight2);
if (difference < -0.01)
{ // the old weights are bigger!
// check if the new routes are bigger than max.
if (route1_size + (weight1_after - weight1) <= max &&
route2_size + (weight2_after - weight1) <= max)
{ // the exchange can happen, both routes stay within bound!
// exchange customer.
int count_before = route1.Count + route2.Count;
//route1.Remove(customer1);
//route2.Remove(customer2);
if (previous_customer1 == next_customer2)
{
throw new Exception();
}
//route1.InsertAfter(previous_customer1, customer2);
//route2.InsertAfter(previous_customer2, customer1);
route1.ReplaceEdgeFrom(previous_customer1, customer2);
route1.ReplaceEdgeFrom(customer2, next_customer1);
route2.ReplaceEdgeFrom(previous_customer2, customer1);
route2.ReplaceEdgeFrom(customer1, next_customer2);
int count_after = route1.Count + route2.Count;
if (count_before != count_after)
{
throw new Exception();
}
double total_after = problem.Time(solution.Route(route1_idx)) +
problem.Time(solution.Route(route2_idx));
if (total_after >= total_before)
{
throw new Exception("this is not an improvement!");
}
return true;
}
}
}
previous_customer2 = customer2; // set the previous customer.
}
}
previous_customer1 = customer1; // set the previous customer.
}
return false;
}
/// <summary>
/// Applies inter-improvements by exchanging parts of the route(s).
/// </summary>
/// <param name="problem"></param>
/// <param name="solution"></param>
/// <param name="route1_idx"></param>
/// <param name="route2_idx"></param>
/// <param name="max"></param>
/// <returns></returns>
public bool Improve(MaxTimeProblem problem, MaxTimeSolution solution,
int route1_idx, int route2_idx, double max)
{
int max_window = 50;
IRoute route1 = solution.Route(route1_idx);
IRoute route2 = solution.Route(route2_idx);
int route1_customers = route1.Count;
int route2_customers = route2.Count;
double[] route1_cumul = problem.TimeCumul(route1);
double[] route2_cumul = problem.TimeCumul(route2);
// build all edge weights.
List<Edge> route1_edges = new List<Edge>(route1.Edges());
List<Edge> route2_edges = new List<Edge>(route2.Edges());
double[] route1_weights = new double[route1_edges.Count];
for (int idx = 0; idx < route1_edges.Count; idx++)
{
Edge edge = route1_edges[idx];
route1_weights[idx] = problem.WeightMatrix[edge.From][edge.To];
}
double[] route2_weights = new double[route2_edges.Count];
for (int idx = 0; idx < route2_edges.Count; idx++)
{
Edge edge = route2_edges[idx];
route2_weights[idx] = problem.WeightMatrix[edge.From][edge.To];
}
List<EdgePair> route2_pairs = new List<EdgePair>();
for (int i_idx = 0; i_idx < route2_edges.Count - 2; i_idx++)
{
Edge i = route2_edges[i_idx];
double i_weight = route2_weights[i_idx];
double weight_before_i = route2_cumul[i_idx];
int k_idx_max = route2_edges.Count;
if (k_idx_max > i_idx + 2 + max_window)
{
k_idx_max = i_idx + 2 + max_window;
}
for (int k_idx = i_idx + 2; k_idx < k_idx_max; k_idx++)
{
Edge k = route2_edges[k_idx];
double k_weight = route2_weights[k_idx];
double weight_after_k = route2_cumul[route2_cumul.Length - 1] - route2_cumul[k_idx + 1];
double weight_between_route = route2_cumul[k_idx] - route2_cumul[i_idx + 1];
route2_pairs.Add(new EdgePair()
{
First = i,
FirstWeight = i_weight,
Second = k,
SecondWeight = k_weight,
Between = new List<int>(route2.Between(i.To, k.From)),
WeightTotal = i_weight + k_weight,
WeightAfter = weight_after_k,
WeightBefore = weight_before_i,
WeightBetween = weight_between_route,
CustomersBetween = k_idx - i_idx
});
}
}
// build all edge pairs.
for (int i_idx = 0; i_idx < route1_edges.Count - 2; i_idx++)
{
Edge i = route1_edges[i_idx];
double i_weight = route1_weights[i_idx];
double weight_before_i = route1_cumul[i_idx];
int k_idx_max = route1_edges.Count;
if (k_idx_max > i_idx + 2 + max_window)
{
k_idx_max = i_idx + 2 + max_window;
}
for (int k_idx = i_idx + 2; k_idx < k_idx_max; k_idx++)
{
Edge k = route1_edges[k_idx];
double k_weight = route1_weights[k_idx];
double weight_after_k = route1_cumul[route1_cumul.Length - 1] - route1_cumul[k_idx + 1];
double weight_between_route = route1_cumul[k_idx] - route1_cumul[i_idx + 1];
EdgePair pair1 = new EdgePair()
{
First = i,
FirstWeight = i_weight,
Second = k,
SecondWeight = k_weight,
Between = new List<int>(route1.Between(i.To, k.From)),
WeightTotal = i_weight + k_weight,
WeightAfter = weight_after_k,
WeightBefore = weight_before_i,
WeightBetween = weight_between_route,
CustomersBetween = k_idx - i_idx
};
foreach (EdgePair pair2 in route2_pairs)
{
double existing_weight = pair1.WeightTotal + pair2.WeightTotal;
//double new_weight = 0;
// get first route new.
double new_weight = problem.WeightMatrix[pair1.First.From][pair2.First.To];
//new_weight = first_route1_new;
if (new_weight > existing_weight - 0.001)
{
continue;
}
double first_route2_new = problem.WeightMatrix[pair2.First.From][pair1.First.To];
new_weight = new_weight + first_route2_new;
if (new_weight > existing_weight - 0.001)
{
continue;
}
double second_route1_new = problem.WeightMatrix[pair1.Second.From][pair2.Second.To];
new_weight = new_weight + second_route1_new;
if (new_weight > existing_weight - 0.001)
{
continue;
}
double second_route2_new = problem.WeightMatrix[pair2.Second.From][pair1.Second.To];
new_weight = new_weight + second_route2_new;
if (new_weight < existing_weight - 0.001)
{ // there is a decrease in total weight; check bounds.
double route1_weight = pair1.WeightBefore + pair2.WeightBetween + pair1.WeightAfter;
double route2_weight = pair2.WeightBefore + pair1.WeightBetween + pair2.WeightAfter;
// calculate the maximum.
int route1_customers_between = pair1.CustomersBetween;
int route2_customers_between = pair1.CustomersBetween;
route1_weight = problem.Time(route1_weight,
route1_customers - route1_customers_between + route2_customers_between);
route2_weight = problem.Time(route2_weight,
route2_customers - route2_customers_between + route1_customers_between);
if (route1_weight < max && route2_weight < max)
{
// MaxTimeSolution solution_copy = solution.Clone() as MaxTimeSolution;
List<int> route1_between = pair1.Between;
List<int> route2_between = pair2.Between;
route1.ReplaceEdgeFrom(pair1.First.From, pair1.Second.To);
route2.ReplaceEdgeFrom(pair2.First.From, pair2.Second.To);
int previous = pair1.First.From;
for (int idx = 0; idx < route2_between.Count; idx++)
{
route1.ReplaceEdgeFrom(previous, route2_between[idx]);
previous = route2_between[idx];
}
route1.ReplaceEdgeFrom(previous, pair1.Second.To);
previous = pair2.First.From;
for (int idx = 0; idx < route1_between.Count; idx++)
{
route2.ReplaceEdgeFrom(previous, route1_between[idx]);
previous = route1_between[idx];
}
route2.ReplaceEdgeFrom(previous, pair2.Second.To);
if (!solution.IsValid())
{
throw new Exception();
}
return true;
}
}
}
}
}
return false;
}
/// <summary>
/// Executes a solver procedure.
/// </summary>
/// <param name="problem"></param>
/// <returns></returns>
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
float lambda = _lambda;
var vrpRouter =
new CheapestInsertionSolverWithImprovements(problem.Max.Value, problem.DeliveryTime.Value, 10, 0.10f, true, _thresholdPercentage, true, 0.75f);
MaxTimeSolution originalSolution = vrpRouter.Solve(
problem);
for (int roundX = 0; roundX < originalSolution.Count; roundX++)
{ // keep looping on rounds.
for (int roundY = 0; roundY < roundX; roundY++)
{ // keep looping on rounds with a smaller index not equal to the current round.
if (roundX != roundY)
{ // routes are different.
if (this.Overlaps(problem, originalSolution.Route(roundX), originalSolution.Route(roundY)))
{ // only check routes that overlap.
double tau = double.MinValue;
var penalizations = new Dictionary<Edge, int>();
//bool improvement = true;
//while (improvement)
//{ // keep looping until no more improvement is found.
// improvement = false;
while (true)
{ // keep trying to improve until the tau limit is exceeded.
// calculate the route sizes before.
double route1ActualBefore = problem.Time(originalSolution.Route(roundX));
double route2ActualBefore = problem.Time(originalSolution.Route(roundY));
// copy orignal solution.
var solution = (originalSolution.Clone() as MaxTimeSolution);
// apply penalties.
foreach (KeyValuePair<Edge, int> penalty in penalizations)
{
problem.Penalize(penalty.Key, (double)penalty.Value * lambda);
}
// apply the inter-route improvements.
int countBefore = solution.Route(roundX).Count + solution.Route(roundY).Count;
int countAfter;
if (this.ImproveInterRoute(problem, solution, roundX, roundY, problem.Max.Value))
{ // the improve inter route succeeded.
if (!solution.IsValid())
{
throw new Exception();
}
//improvement_inter = true;
countAfter = solution.Route(roundX).Count + solution.Route(roundY).Count;
if (countBefore != countAfter)
{
throw new Exception();
}
// apply the intra-route improvements.
solution[roundX] = this.ImproveIntraRoute(problem, solution.Route(roundX), solution[roundX]);
solution[roundY] = this.ImproveIntraRoute(problem, solution.Route(roundY), solution[roundY]);
// recalculate weights.
solution[roundX] = problem.Time(solution.Route(roundX));
solution[roundY] = problem.Time(solution.Route(roundY));
}
// check customer counts.
countAfter = solution.Route(roundX).Count + solution.Route(roundY).Count;
if (countBefore != countAfter)
{
throw new Exception();
}
// undo the penalizations.
problem.ResetPenalizations();
// check against the orginal objective function.
double route1ActualAfter = problem.Time(solution.Route(roundX));
double route2ActualAfter = problem.Time(solution.Route(roundY));
if (route1ActualAfter + route2ActualAfter < route1ActualBefore + route2ActualBefore - 0.001 &&
route1ActualAfter < problem.Max.Value && route2ActualAfter < problem.Max.Value)
{ // there is improvement!
originalSolution = solution;
//improvement = true;
OsmSharp.Logging.Log.TraceEvent("OsmSharp.Routing.VRP.NoDepot.MaxTime.VNS.GuidedVNS", TraceEventType.Information,
"IMPROVEMENT: {0}->{1}",
route1ActualBefore + route2ActualBefore, route1ActualAfter + route2ActualAfter);
}
// select arc to be penalized.
IRoute route1 = originalSolution.Route(roundX);
IRoute route2 = originalSolution.Route(roundY);
double u = double.MinValue;
var penalizingEdge = new Edge();
double totalP = 0;
foreach (Edge edge in route1.Edges())
{
int edgeP;
if (!penalizations.TryGetValue(edge, out edgeP))
{
edgeP = 0;
}
totalP = totalP + edgeP;
double edgeU = ((lambda * (double)edgeP) + problem.WeightMatrix[edge.From][edge.To]) /
((double)edgeP + 1.0);
if (u <= edgeU)
{
penalizingEdge = edge;
u = edgeU;
}
}
foreach (Edge edge in route2.Edges())
{
int edgeP;
if (!penalizations.TryGetValue(edge, out edgeP))
{
edgeP = 0;
}
totalP = totalP + edgeP;
double edgeU = ((lambda * (double)edgeP) + problem.WeightMatrix[edge.From][edge.To]) /
((double)edgeP + 1.0);
if (u <= edgeU)
{
penalizingEdge = edge;
u = edgeU;
}
}
// actually penalize the edge.
int p;
if (!penalizations.TryGetValue(penalizingEdge, out p))
{
p = 1;
}
else
{
p++;
}
penalizations[penalizingEdge] = p;
// evaluate or set tau.
if (tau > double.MinValue)
{ // evaluate if penalizations should end.
if (tau <= lambda * totalP)
{ // the penalization should end!
break;
}
}
else
{ // first edge being penalized.
tau = lambda * problem.WeightMatrix[penalizingEdge.From][penalizingEdge.To] / 10;
}
}
}
}
}
}
return originalSolution;
}
/// <summary>
/// Executes a solver procedure.
/// </summary>
/// <param name="problem"></param>
/// <returns></returns>
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
float lambda = _lambda;
var vrpRouter =
new CheapestInsertionSolverWithImprovements(problem.Max.Value, problem.DeliveryTime.Value, 10, 0.10f, true, _thresholdPercentage, true, 0.75f);
MaxTimeSolution originalSolution = vrpRouter.Solve(
problem);
for (int roundX = 0; roundX < originalSolution.Count; roundX++)
{ // keep looping on rounds.
for (int roundY = 0; roundY < roundX; roundY++)
{ // keep looping on rounds with a smaller index not equal to the current round.
if (roundX != roundY)
{ // routes are different.
if (this.Overlaps(problem, originalSolution.Route(roundX), originalSolution.Route(roundY)))
{ // only check routes that overlap.
double tau = double.MinValue;
var penalizations = new Dictionary <Edge, int>();
//bool improvement = true;
//while (improvement)
//{ // keep looping until no more improvement is found.
// improvement = false;
while (true)
{ // keep trying to improve until the tau limit is exceeded.
// calculate the route sizes before.
double route1ActualBefore = problem.Time(originalSolution.Route(roundX));
double route2ActualBefore = problem.Time(originalSolution.Route(roundY));
// copy orignal solution.
var solution = (originalSolution.Clone() as MaxTimeSolution);
// apply penalties.
foreach (KeyValuePair <Edge, int> penalty in penalizations)
{
problem.Penalize(penalty.Key, (double)penalty.Value * lambda);
}
// apply the inter-route improvements.
int countBefore = solution.Route(roundX).Count + solution.Route(roundY).Count;
int countAfter;
if (this.ImproveInterRoute(problem, solution, roundX, roundY, problem.Max.Value))
{ // the improve inter route succeeded.
if (!solution.IsValid())
{
throw new Exception();
}
//improvement_inter = true;
countAfter = solution.Route(roundX).Count + solution.Route(roundY).Count;
if (countBefore != countAfter)
{
throw new Exception();
}
// apply the intra-route improvements.
solution[roundX] = this.ImproveIntraRoute(problem, solution.Route(roundX), solution[roundX]);
solution[roundY] = this.ImproveIntraRoute(problem, solution.Route(roundY), solution[roundY]);
// recalculate weights.
solution[roundX] = problem.Time(solution.Route(roundX));
solution[roundY] = problem.Time(solution.Route(roundY));
}
// check customer counts.
countAfter = solution.Route(roundX).Count + solution.Route(roundY).Count;
if (countBefore != countAfter)
{
throw new Exception();
}
// undo the penalizations.
problem.ResetPenalizations();
// check against the orginal objective function.
double route1ActualAfter = problem.Time(solution.Route(roundX));
double route2ActualAfter = problem.Time(solution.Route(roundY));
if (route1ActualAfter + route2ActualAfter < route1ActualBefore + route2ActualBefore - 0.001 &&
route1ActualAfter < problem.Max.Value && route2ActualAfter < problem.Max.Value)
{ // there is improvement!
originalSolution = solution;
//improvement = true;
OsmSharp.Logging.Log.TraceEvent("OsmSharp.Routing.VRP.NoDepot.MaxTime.VNS.GuidedVNS", TraceEventType.Information,
"IMPROVEMENT: {0}->{1}",
route1ActualBefore + route2ActualBefore, route1ActualAfter + route2ActualAfter);
}
// select arc to be penalized.
IRoute route1 = originalSolution.Route(roundX);
IRoute route2 = originalSolution.Route(roundY);
double u = double.MinValue;
var penalizingEdge = new Edge();
double totalP = 0;
foreach (Edge edge in route1.Edges())
{
int edgeP;
if (!penalizations.TryGetValue(edge, out edgeP))
{
edgeP = 0;
}
totalP = totalP + edgeP;
double edgeU = ((lambda * (double)edgeP) + problem.WeightMatrix[edge.From][edge.To]) /
((double)edgeP + 1.0);
if (u <= edgeU)
{
penalizingEdge = edge;
u = edgeU;
}
}
foreach (Edge edge in route2.Edges())
{
int edgeP;
if (!penalizations.TryGetValue(edge, out edgeP))
{
edgeP = 0;
}
totalP = totalP + edgeP;
double edgeU = ((lambda * (double)edgeP) + problem.WeightMatrix[edge.From][edge.To]) /
((double)edgeP + 1.0);
if (u <= edgeU)
{
penalizingEdge = edge;
u = edgeU;
}
}
// actually penalize the edge.
int p;
if (!penalizations.TryGetValue(penalizingEdge, out p))
{
p = 1;
}
else
{
p++;
}
penalizations[penalizingEdge] = p;
// evaluate or set tau.
if (tau > double.MinValue)
{ // evaluate if penalizations should end.
if (tau <= lambda * totalP)
{ // the penalization should end!
break;
}
}
else
{ // first edge being penalized.
tau = lambda * problem.WeightMatrix[penalizingEdge.From][penalizingEdge.To] / 10;
}
}
}
}
}
}
return(originalSolution);
}
/// <summary>
/// Applies inter-improvements by exchanging parts of the route(s).
/// </summary>
/// <param name="problem"></param>
/// <param name="solution"></param>
/// <param name="route1_idx"></param>
/// <param name="route2_idx"></param>
/// <param name="max"></param>
/// <returns></returns>
public bool Improve(MaxTimeProblem problem, MaxTimeSolution solution,
int route1_idx, int route2_idx, double max)
{
int max_window = 40;
IRoute route1 = solution.Route(route1_idx);
IRoute route2 = solution.Route(route2_idx);
int route1_customers = route1.Count;
int route2_customers = route2.Count;
double[] route1_cumul = problem.TimeCumul(route1);
double[] route2_cumul = problem.TimeCumul(route2);
// build all edge weights.
List <Edge> route1_edges = new List <Edge>(route1.Edges());
List <Edge> route2_edges = new List <Edge>(route2.Edges());
double[] route1_weights = new double[route1_edges.Count];
for (int idx = 0; idx < route1_edges.Count; idx++)
{
Edge edge = route1_edges[idx];
route1_weights[idx] = problem.WeightMatrix[edge.From][edge.To];
}
double[] route2_weights = new double[route2_edges.Count];
for (int idx = 0; idx < route2_edges.Count; idx++)
{
Edge edge = route2_edges[idx];
route2_weights[idx] = problem.WeightMatrix[edge.From][edge.To];
}
List <EdgePair> route2_pairs = new List <EdgePair>();
for (int i_idx = 0; i_idx < route2_edges.Count - 2; i_idx++)
{
Edge i = route2_edges[i_idx];
double i_weight = route2_weights[i_idx];
double weight_before_i = route2_cumul[i_idx];
int k_idx_max = route2_edges.Count;
if (k_idx_max > i_idx + 2 + max_window)
{
k_idx_max = i_idx + 2 + max_window;
}
for (int k_idx = i_idx + 2; k_idx < k_idx_max; k_idx++)
{
Edge k = route2_edges[k_idx];
double k_weight = route2_weights[k_idx];
double weight_after_k = route2_cumul[route2_cumul.Length - 1] - route2_cumul[k_idx + 1];
double weight_between_route = route2_cumul[k_idx] - route2_cumul[i_idx + 1];
route2_pairs.Add(new EdgePair()
{
First = i,
FirstWeight = i_weight,
Second = k,
SecondWeight = k_weight,
Between = new List <int>(route2.Between(i.To, k.From)),
WeightTotal = i_weight + k_weight,
WeightAfter = weight_after_k,
WeightBefore = weight_before_i,
WeightBetween = weight_between_route,
CustomersBetween = k_idx - i_idx
});
}
}
// build all edge pairs.
for (int i_idx = 0; i_idx < route1_edges.Count - 2; i_idx++)
{
Edge i = route1_edges[i_idx];
double i_weight = route1_weights[i_idx];
double weight_before_i = route1_cumul[i_idx];
int k_idx_max = route1_edges.Count;
if (k_idx_max > i_idx + 2 + max_window)
{
k_idx_max = i_idx + 2 + max_window;
}
for (int k_idx = i_idx + 2; k_idx < k_idx_max; k_idx++)
{
Edge k = route1_edges[k_idx];
double k_weight = route1_weights[k_idx];
double weight_after_k = route1_cumul[route1_cumul.Length - 1] - route1_cumul[k_idx + 1];
double weight_between_route = route1_cumul[k_idx] - route1_cumul[i_idx + 1];
EdgePair pair1 = new EdgePair()
{
First = i,
FirstWeight = i_weight,
Second = k,
SecondWeight = k_weight,
Between = new List <int>(route1.Between(i.To, k.From)),
WeightTotal = i_weight + k_weight,
WeightAfter = weight_after_k,
WeightBefore = weight_before_i,
WeightBetween = weight_between_route,
CustomersBetween = k_idx - i_idx
};
foreach (EdgePair pair2 in route2_pairs)
{
double existing_weight = pair1.WeightTotal + pair2.WeightTotal;
//double new_weight = 0;
// get first route new.
double new_weight = problem.WeightMatrix[pair1.First.From][pair2.First.To];
//new_weight = first_route1_new;
if (new_weight > existing_weight - 0.001)
{
continue;
}
double first_route2_new = problem.WeightMatrix[pair2.First.From][pair1.First.To];
new_weight = new_weight + first_route2_new;
if (new_weight > existing_weight - 0.001)
{
continue;
}
double second_route1_new = problem.WeightMatrix[pair1.Second.From][pair2.Second.To];
new_weight = new_weight + second_route1_new;
if (new_weight > existing_weight - 0.001)
{
continue;
}
double second_route2_new = problem.WeightMatrix[pair2.Second.From][pair1.Second.To];
new_weight = new_weight + second_route2_new;
if (new_weight < existing_weight - 0.001)
{ // there is a decrease in total weight; check bounds.
double route1_weight = pair1.WeightBefore + pair2.WeightBetween + pair1.WeightAfter;
double route2_weight = pair2.WeightBefore + pair1.WeightBetween + pair2.WeightAfter;
// calculate the maximum.
int route1_customers_between = pair1.CustomersBetween;
int route2_customers_between = pair1.CustomersBetween;
route1_weight = problem.Time(route1_weight,
route1_customers - route1_customers_between + route2_customers_between);
route2_weight = problem.Time(route2_weight,
route2_customers - route2_customers_between + route1_customers_between);
if (route1_weight < max && route2_weight < max)
{
MaxTimeSolution solution_copy = solution.Clone() as MaxTimeSolution;
List <int> route1_between = pair1.Between;
List <int> route2_between = pair2.Between;
route1.ReplaceEdgeFrom(pair1.First.From, pair1.Second.To);
route2.ReplaceEdgeFrom(pair2.First.From, pair2.Second.To);
int previous = pair1.First.From;
for (int idx = 0; idx < route2_between.Count; idx++)
{
route1.ReplaceEdgeFrom(previous, route2_between[idx]);
previous = route2_between[idx];
}
route1.ReplaceEdgeFrom(previous, pair1.Second.To);
previous = pair2.First.From;
for (int idx = 0; idx < route1_between.Count; idx++)
{
route2.ReplaceEdgeFrom(previous, route1_between[idx]);
previous = route1_between[idx];
}
route2.ReplaceEdgeFrom(previous, pair2.Second.To);
if (!solution.IsValid())
{
throw new Exception();
}
return(true);
}
}
}
}
}
return(false);
}
/// <summary>
/// Tries a relocation of the customers in route1 to route2.
/// </summary>
/// <param name="problem"></param>
/// <param name="solution"></param>
/// <param name="route1_idx"></param>
/// <param name="route2_idx"></param>
/// <param name="max"></param>
/// <returns></returns>
private bool RelocateFromTo(MaxTimeProblem problem, MaxTimeSolution solution,
int route1_idx, int route2_idx, double max)
{
int previous = -1;
int current = -1;
IRoute route1 = solution.Route(route1_idx);
IRoute route2 = solution.Route(route2_idx);
double route2_weight = solution[route2_idx];
foreach (int next in route1)
{
if (previous >= 0 && current >= 0)
{ // consider the next customer.
int count_before1 = route1.Count;
int count_before2 = route2.Count;
// string route1_string = route1.ToString();
// string route2_string = route2.ToString();
if (this.ConsiderCustomer(problem, route2, previous, current, next, route2_weight, max))
{
route1.ReplaceEdgeFrom(previous, next);
int count_after = route1.Count + route2.Count;
if ((count_before1 + count_before2) != count_after)
{
throw new Exception();
}
return true;
}
}
previous = current;
current = next;
}
return false;
}
/// <summary>
/// Executes a solver procedure.
/// </summary>
/// <param name="problem"></param>
/// <returns></returns>
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
// create the calculator.
MaxTimeCalculator calculator = new MaxTimeCalculator(problem);
// create the solution.
MaxTimeSolution solution = new MaxTimeSolution(problem.Size, true);
// keep placing customer until none are left.
List <int> customers = new List <int>(problem.Customers);
while (customers.Count > 0)
{
// select a customer using some heuristic.
int customer_idx = OsmSharp.Math.Random.StaticRandomGenerator.Get().Generate(customers.Count);
int customer = customers[customer_idx];
customers.Remove(customer);
// start a route r.
double current_route_weight = 0;
IRoute current_route = solution.Add(customer);
//Console.WriteLine("Starting new route with {0}", customer);
while (customers.Count > 0)
{
// calculate the best placement.
CheapestInsertionResult result =
CheapestInsertionHelper.CalculateBestPlacement(problem, current_route, customers);
// calculate the new weight.
double potential_weight = calculator.CalculateOneRouteIncrease(current_route_weight, result.Increase);
// cram as many customers into one route as possible.
if (potential_weight < problem.Max.Value)
{
// insert the customer, it is
customers.Remove(result.Customer);
//current_route.InsertAfterAndRemove(result.CustomerBefore, result.Customer, result.CustomerAfter);
current_route.InsertAfter(result.CustomerBefore, result.Customer);
current_route_weight = potential_weight;
//// improve if needed.
////if (improvement_probalitity > OsmSharp.Math.Random.StaticRandomGenerator.Get().Generate(1))
//if (((problem.Size - customers.Count) % _k) == 0)
//{ // an improvement is descided.
// current_route_weight = this.ImproveIntraRoute(problem,
// current_route, current_route_weight);
//}
}
else
{// ok we are done!
//// apply the intra-route heuristics.
//for (int route_idx = 0; route_idx < solution.Count - 1; route_idx++)
//{ // apply the intra-route heurstic between the new and all existing routes.
// this.ImproveInterRoute(problem, solution.Route(route_idx), current_route);
//}
//// apply the inter-route heuristics.
//for (int route_idx = 0; route_idx < solution.Count; route_idx++)
//{ // apply heurstic for each route.
// IRoute route = solution.Route(route_idx);
// this.ImproveIntraRoute(problem, current_route, current_route_weight);
//}
// break the route.
break;
}
}
}
return(solution);
}
/// <summary>
/// Executes a solver procedure.
/// </summary>
/// <param name="problem"></param>
/// <returns></returns>
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
MaxTimeCalculator calculator = new MaxTimeCalculator(problem);
// get the seed customers.
ICollection <int> seeds = _seed_selector.SelectSeeds(
problem, _k);
double[] weights = new double[seeds.Count];
// start the seed routes.
List <int> selectable_customers = problem.Customers;
MaxTimeSolution routes = new MaxTimeSolution(
problem.Size, true);
foreach (int seed in seeds)
{
routes.Add(seed);
selectable_customers.Remove(seed);
}
if (!routes.IsValid())
{
throw new Exception();
}
// keep a list of cheapest insertions.
IInsertionCosts costs = new BinaryHeapInsertionCosts();
// keep looping until all customers have been placed.
while (selectable_customers.Count > 0)
{
// try and place into every route.
CheapestInsertionResult best_result = new CheapestInsertionResult();
best_result.Increase = float.MaxValue;
int best_route_idx = -1;
CheapestInsertionResult best_result_above_max = new CheapestInsertionResult();
best_result_above_max.Increase = float.MaxValue;
int best_route_above_max_idx = -1;
for (int route_idx = 0; route_idx < routes.Count; route_idx++)
{
IRoute current_route = routes.Route(route_idx);
// choose the next customer.
CheapestInsertionResult result =
CheapestInsertionHelper.CalculateBestPlacement(problem, current_route, selectable_customers, costs);
if (result.Customer == result.CustomerAfter)
{
throw new Exception();
}
// get the current weight
double weight = weights[route_idx];
if (result.Increase < best_result.Increase)
{
if (weight + result.Increase + calculator.DeliveryTime < problem.Max.Value)
{ // route will still be inside bounds.
best_result = result;
best_route_idx = route_idx;
}
else
{ // route will become above max.
if (result.Increase < best_result_above_max.Increase)
{
best_result_above_max = result;
best_route_above_max_idx = route_idx;
}
}
}
}
// do the placement if a placement is found without max violation.
// else do the placement in the above max route.
CheapestInsertionResult placement_result = new CheapestInsertionResult();
placement_result.Increase = double.MaxValue;
int placement_result_idx = -1;
if (best_route_idx >= 0)
{ // best placement found.
placement_result = best_result;
placement_result_idx = best_route_idx;
}
else
{ // best placement found but only above max.
placement_result = best_result_above_max;
placement_result_idx = best_route_above_max_idx;
}
// do the actual placement.
weights[placement_result_idx] = calculator.CalculateOneRouteIncrease(
weights[placement_result_idx], placement_result.Increase);
selectable_customers.Remove(placement_result.Customer);
//routes.Route(placement_result_idx).InsertAfterAndRemove(
// placement_result.CustomerBefore, placement_result.Customer, placement_result.CustomerAfter);
routes.Route(placement_result_idx).InsertAfter(
placement_result.CustomerBefore, placement_result.Customer);
if (!routes.IsValid())
{
throw new Exception();
}
}
return(routes);
}
/// <summary>
/// Executes a solver procedure.
/// </summary>
/// <param name="problem"></param>
/// <returns></returns>
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
MaxTimeCalculator calculator = new MaxTimeCalculator(problem);
// get the seed customers.
ICollection<int> seeds = _seed_selector.SelectSeeds(
problem, _k);
double[] weights = new double[seeds.Count];
// start the seed routes.
List<int> selectable_customers = problem.Customers;
MaxTimeSolution routes = new MaxTimeSolution(
problem.Size, true);
foreach (int seed in seeds)
{
routes.Add(seed);
selectable_customers.Remove(seed);
}
if (!routes.IsValid())
{
throw new Exception();
}
// keep a list of cheapest insertions.
IInsertionCosts costs = new BinaryHeapInsertionCosts();
// keep looping until all customers have been placed.
while (selectable_customers.Count > 0)
{
// try and place into every route.
CheapestInsertionResult best_result = new CheapestInsertionResult();
best_result.Increase = float.MaxValue;
int best_route_idx = -1;
CheapestInsertionResult best_result_above_max = new CheapestInsertionResult();
best_result_above_max.Increase = float.MaxValue;
int best_route_above_max_idx = -1;
for (int route_idx = 0; route_idx < routes.Count; route_idx++)
{
IRoute current_route = routes.Route(route_idx);
// choose the next customer.
CheapestInsertionResult result =
CheapestInsertionHelper.CalculateBestPlacement(problem, current_route, selectable_customers, costs);
if (result.Customer == result.CustomerAfter)
{
throw new Exception();
}
// get the current weight
double weight = weights[route_idx];
if (result.Increase < best_result.Increase)
{
if (weight + result.Increase + calculator.DeliveryTime < problem.Max.Value)
{ // route will still be inside bounds.
best_result = result;
best_route_idx = route_idx;
}
else
{ // route will become above max.
if (result.Increase < best_result_above_max.Increase)
{
best_result_above_max = result;
best_route_above_max_idx = route_idx;
}
}
}
}
// do the placement if a placement is found without max violation.
// else do the placement in the above max route.
CheapestInsertionResult placement_result = new CheapestInsertionResult();
placement_result.Increase = double.MaxValue;
int placement_result_idx = -1;
if (best_route_idx >= 0)
{ // best placement found.
placement_result = best_result;
placement_result_idx = best_route_idx;
}
else
{ // best placement found but only above max.
placement_result = best_result_above_max;
placement_result_idx = best_route_above_max_idx;
}
// do the actual placement.
weights[placement_result_idx] = calculator.CalculateOneRouteIncrease(
weights[placement_result_idx], placement_result.Increase);
selectable_customers.Remove(placement_result.Customer);
//routes.Route(placement_result_idx).InsertAfterAndRemove(
// placement_result.CustomerBefore, placement_result.Customer, placement_result.CustomerAfter);
routes.Route(placement_result_idx).InsertAfter(
placement_result.CustomerBefore, placement_result.Customer);
if (!routes.IsValid())
{
throw new Exception();
}
}
return routes;
}
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
MaxTimeCalculator calculator = new MaxTimeCalculator(
problem);
// generate a ATSP solution.
IRoute tsp_solution = _tsp_solution;
if (tsp_solution == null)
{
tsp_solution = _tsp_solver.Solve(new TSPProblem(problem));
}
// generate subtours from this solution.
MaxTimeSolution solution = new MaxTimeSolution(problem.Size, true);
// select a random start point.
int start = OsmSharp.Math.Random.StaticRandomGenerator.Get().Generate(problem.Size);
// start the first tour.
int placed = 0;
int previous = -1;
// place the first customer.
double weight = 0;
double total_weight = 0;
IRoute route = solution.Add(start);
previous = start;
while (placed < problem.Size)
{
// get the next customer from the tsp solution.
int next = tsp_solution.GetNeigbours(previous)[0];
// get the weight to the current start.
double weight_to_next = problem.WeightMatrix[previous][next];
double weight_to_start = problem.WeightMatrix[next][start];
total_weight = calculator.CalculateOneRouteIncrease(
weight, weight_to_next + weight_to_start);
weight = calculator.CalculateOneRouteIncrease(
weight, weight_to_next);
if (total_weight > problem.Max.Value)
{ // start a new route.
route = solution.Add(next);
weight = 0;
}
else
{ // just insert the next customer.
route.InsertAfter(previous, next);
//route.InsertAfterAndRemove(previous, next, -1);
}
// set the previous.
previous = next;
placed++;
}
if (!solution.IsValid())
{
throw new Exception();
}
StringBuilder builder = new StringBuilder();
builder.Append("[");
total_weight = 0;
for (int idx = 0; idx < solution.Count; idx++)
{
//IRoute route = routes.Route(idx);
route = solution.Route(idx);
weight = calculator.CalculateOneRoute(route);
builder.Append(" ");
builder.Append(weight);
builder.Append(" ");
total_weight = total_weight + weight;
}
builder.Append("]");
builder.Append(total_weight);
builder.Append(": ");
builder.Append(calculator.Calculate(solution));
Console.WriteLine(builder.ToString());
return(solution);
}
/// <summary>
/// Apply some improvements between the given routes and returns the resulting weight.
/// </summary>
/// <param name="problem"></param>
/// <param name="solution"></param>
/// <param name="route1Idx"></param>
/// <param name="route2Idx"></param>
/// <param name="max"></param>
/// <returns></returns>
private bool ImproveInterRoute(MaxTimeProblem problem, MaxTimeSolution solution,
int route1Idx, int route2Idx, double max)
{
// get the routes.
IRoute route1 = solution.Route(route1Idx);
IRoute route2 = solution.Route(route2Idx);
int countBefore = route1.Count + route2.Count;
// loop over all improvement operations.
bool globalImprovement = false;
foreach (IInterImprovement improvementOperation in _inter_improvements)
{ // try the current improvement operations.
bool improvement = true;
while (improvement)
{ // keep looping when there is improvement.
improvement = false;
double totalBefore = problem.Time(solution.Route(route1Idx)) +
problem.Time(solution.Route(route2Idx));
if (improvementOperation.Improve(problem, solution, route1Idx, route2Idx, max))
{ // there was an improvement.
improvement = true;
globalImprovement = true;
// check if the route is valid.
if (!route1.IsValid())
{
throw new Exception();
}
if (!route2.IsValid())
{
throw new Exception();
}
int countAfter = route1.Count + route2.Count;
if (countBefore != countAfter)
{
throw new Exception();
}
double totalAfter = problem.Time(solution.Route(route1Idx)) +
problem.Time(solution.Route(route2Idx));
if (totalAfter >= totalBefore)
{
throw new Exception("this is not an improvement!");
}
OsmSharp.Logging.Log.TraceEvent("OsmSharp.Routing.VRP.NoDepot.MaxTime.VNS.GuidedVNS", TraceEventType.Information,
"Inter-improvement found {0}<->{1}: {2} ({3}->{4})",
route1Idx, route2Idx, improvementOperation.Name, totalBefore, totalAfter);
// recalculate weights.
solution[route1Idx] = problem.Time(solution.Route(route1Idx));
solution[route2Idx] = problem.Time(solution.Route(route2Idx));
//break;
}
else if (!improvementOperation.IsSymmetric &&
improvementOperation.Improve(problem, solution, route2Idx, route1Idx, max))
{ // also do the improvement the other way around when not symmetric.
improvement = true;
globalImprovement = true;
// check if the route is valid.
if (!route1.IsValid())
{
throw new Exception();
}
if (!route2.IsValid())
{
throw new Exception();
}
int countAfter = route1.Count + route2.Count;
if (countBefore != countAfter)
{
throw new Exception();
}
double totalAfter = problem.Time(solution.Route(route1Idx)) +
problem.Time(solution.Route(route2Idx));
if (totalAfter >= totalBefore)
{
throw new Exception("this is not an improvement!");
}
OsmSharp.Logging.Log.TraceEvent("OsmSharp.Routing.VRP.NoDepot.MaxTime.VNS.GuidedVNS", TraceEventType.Information,
"Inter-improvement found {0}<->{1}: {2} ({3}->{4})",
route2Idx, route1Idx, improvementOperation.Name, totalBefore, totalAfter);
// recalculate weights.
solution[route1Idx] = problem.Time(solution.Route(route1Idx));
solution[route2Idx] = problem.Time(solution.Route(route2Idx));
//break;
}
}
}
return(globalImprovement);
}
/// <summary>
/// Tries to relocate customers using the source the same as the CrossExchange but places customers using cheapest insertion.
/// </summary>
/// <param name="problem"></param>
/// <param name="solution"></param>
/// <param name="route1_idx"></param>
/// <param name="route2_idx"></param>
/// <param name="max"></param>
/// <returns></returns>
public bool Improve(MaxTimeProblem problem, MaxTimeSolution solution,
int route1_idx, int route2_idx, double max)
{
int max_window = 10;
IRoute route1 = solution.Route(route1_idx);
IRoute route2 = solution.Route(route2_idx);
double total_before = problem.Time(solution.Route(route1_idx)) +
problem.Time(solution.Route(route2_idx));
int route1_customers = route1.Count;
int route2_customers = route2.Count;
double[] route1_cumul = problem.TimeCumul(route1);
double[] route2_cumul = problem.TimeCumul(route2);
// build all edge weights.
List <Edge> route1_edges = new List <Edge>(route1.Edges());
List <Edge> route2_edges = new List <Edge>(route2.Edges());
double[] route1_weights = new double[route1_edges.Count];
for (int idx = 0; idx < route1_edges.Count; idx++)
{
Edge edge = route1_edges[idx];
route1_weights[idx] = problem.WeightMatrix[edge.From][edge.To];
}
double[] route2_weights = new double[route2_edges.Count];
for (int idx = 0; idx < route2_edges.Count; idx++)
{
Edge edge = route2_edges[idx];
route2_weights[idx] = problem.WeightMatrix[edge.From][edge.To];
}
List <EdgePair> route2_pairs = new List <EdgePair>();
for (int i_idx = 0; i_idx < route2_edges.Count - 2; i_idx++)
{
Edge i = route2_edges[i_idx];
double i_weight = route2_weights[i_idx];
double weight_before_i = route2_cumul[i_idx];
int k_idx_max = route2_edges.Count;
if (k_idx_max > i_idx + 2 + max_window)
{
k_idx_max = i_idx + 2 + max_window;
}
for (int k_idx = i_idx + 2; k_idx < k_idx_max; k_idx++)
{
Edge k = route2_edges[k_idx];
double k_weight = route2_weights[k_idx];
double weight_after_k = route2_cumul[route2_cumul.Length - 1] - route2_cumul[k_idx + 1];
double weight_between_route = route2_cumul[k_idx] - route2_cumul[i_idx + 1];
route2_pairs.Add(new EdgePair()
{
First = i,
FirstWeight = i_weight,
Second = k,
SecondWeight = k_weight,
Between = new List <int>(route2.Between(i.To, k.From)),
WeightTotal = i_weight + k_weight,
WeightAfter = weight_after_k,
WeightBefore = weight_before_i,
WeightBetween = weight_between_route,
CustomersBetween = k_idx - i_idx
});
}
}
// try to relocate all and find best pair.
double route1_weight = route1_cumul[route1_cumul.Length - 1];
EdgePair best = null;
CheapestInsertionResult best_result = new CheapestInsertionResult();
double best_extra = double.MaxValue;
foreach (EdgePair pair2 in route2_pairs)
{
// calculate cheapest insertion.
CheapestInsertionResult result =
CheapestInsertionHelper.CalculateBestPlacement(problem, route1,
pair2.First.To, pair2.Second.From);
double extra_route2 = problem.WeightMatrix[pair2.First.From][pair2.Second.To];
// check if the result has a net-decrease.
if (result.Increase + extra_route2 < pair2.WeightTotal - 0.01)
{ // there is a net decrease.
// calculate the real increase.
double new_weight = problem.Time(route1_weight + result.Increase + pair2.WeightBetween, route1_customers +
pair2.CustomersBetween);
// check the max.
if (new_weight < max && new_weight < best_extra)
{ // the route is smaller than max.
best_extra = new_weight;
best_result = result;
best = pair2;
}
}
}
if (best != null)
{
if (route2.Last == best.Second.To)
{
//throw new Exception();
}
route2.ReplaceEdgeFrom(best.First.From, best.Second.To);
int previous = best_result.CustomerBefore;
foreach (int customer in best.Between)
{
route1.ReplaceEdgeFrom(previous, customer);
previous = customer;
}
route1.ReplaceEdgeFrom(previous, best_result.CustomerAfter);
// check validity.
if (!route2.IsValid())
{
throw new Exception();
}
if (!route1.IsValid())
{
throw new Exception();
}
if (route1.Count + route2.Count != route1_customers + route2_customers)
{
throw new Exception();
}
double total_after = problem.Time(solution.Route(route1_idx)) +
problem.Time(solution.Route(route2_idx));
if (total_after >= total_before)
{
throw new Exception("this is not an improvement!");
}
return(true);
}
return(false);
}
/// <summary>
/// Executes a solver procedure.
/// </summary>
/// <param name="problem"></param>
/// <returns></returns>
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
float lambda = _lambda;
CheapestInsertionSolverWithImprovements vrp_router =
new CheapestInsertionSolverWithImprovements(problem.Max.Value, problem.DeliveryTime.Value, 10, 0.10f, true, _threshold_percentage, true, 0.75f);
MaxTimeSolution original_solution = vrp_router.Solve(
problem);
for (int round_x = 0; round_x < original_solution.Count; round_x++)
{ // keep looping on rounds.
for (int round_y = 0; round_y < round_x; round_y++)
{ // keep looping on rounds with a smaller index not equal to the current round.
if (round_x != round_y)
{ // routes are different.
if (this.Overlaps(problem, original_solution.Route(round_x), original_solution.Route(round_y)))
{ // only check routes that overlap.
double tau = double.MinValue;
Dictionary<Edge, int> penalizations = new Dictionary<Edge, int>();
//bool improvement = true;
//while (improvement)
//{ // keep looping until no more improvement is found.
// improvement = false;
while (true)
{ // keep trying to improve until the tau limit is exceeded.
// calculate the route sizes before.
double route1_actual_before = problem.Time(original_solution.Route(round_x));
double route2_actual_before = problem.Time(original_solution.Route(round_y));
// copy orignal solution.
MaxTimeSolution solution = (original_solution.Clone() as MaxTimeSolution);
// apply penalties.
foreach (KeyValuePair<Edge, int> penalty in penalizations)
{
problem.Penalize(penalty.Key, (double)penalty.Value * lambda);
}
// apply the inter-route improvements.
int count_before = solution.Route(round_x).Count + solution.Route(round_y).Count;
int count_after;
if (this.ImproveInterRoute(problem, solution, round_x, round_y, problem.Max.Value))
{ // the improve inter route succeeded.
if (!solution.IsValid())
{
throw new Exception();
}
//improvement_inter = true;
count_after = solution.Route(round_x).Count + solution.Route(round_y).Count;
if (count_before != count_after)
{
throw new Exception();
}
// apply the intra-route improvements.
solution[round_x] = this.ImproveIntraRoute(problem, solution.Route(round_x), solution[round_x]);
solution[round_y] = this.ImproveIntraRoute(problem, solution.Route(round_y), solution[round_y]);
// recalculate weights.
solution[round_x] = problem.Time(solution.Route(round_x));
solution[round_y] = problem.Time(solution.Route(round_y));
}
// check customer counts.
count_after = solution.Route(round_x).Count + solution.Route(round_y).Count;
if (count_before != count_after)
{
throw new Exception();
}
// undo the penalizations.
problem.ResetPenalizations();
// check against the orginal objective function.
double route1_actual_after = problem.Time(solution.Route(round_x));
double route2_actual_after = problem.Time(solution.Route(round_y));
if (route1_actual_after + route2_actual_after < route1_actual_before + route2_actual_before - 0.001 &&
route1_actual_after < problem.Max.Value && route2_actual_after < problem.Max.Value)
{ // there is improvement!
original_solution = solution;
//improvement = true;
OsmSharp.Tools.Output.OutputStreamHost.WriteLine("IMPROVEMENT: {0}->{1}",
route1_actual_before + route2_actual_before, route1_actual_after + route2_actual_after);
}
// select arc to be penalized.
IRoute route1 = original_solution.Route(round_x);
IRoute route2 = original_solution.Route(round_y);
double u = double.MinValue;
Edge penalizing_edge = new Edge();
double total_p = 0;
foreach (Edge edge in route1.Edges())
{
int edge_p;
if (!penalizations.TryGetValue(edge, out edge_p))
{
edge_p = 0;
}
total_p = total_p + edge_p;
double edge_u = ((lambda * (double)edge_p) + problem.WeightMatrix[edge.From][edge.To]) /
((double)edge_p + 1.0);
if (u <= edge_u)
{
penalizing_edge = edge;
u = edge_u;
}
}
foreach (Edge edge in route2.Edges())
{
int edge_p;
if (!penalizations.TryGetValue(edge, out edge_p))
{
edge_p = 0;
}
total_p = total_p + edge_p;
double edge_u = ((lambda * (double)edge_p) + problem.WeightMatrix[edge.From][edge.To]) /
((double)edge_p + 1.0);
if (u <= edge_u)
{
penalizing_edge = edge;
u = edge_u;
}
}
// actually penalize the edge.
int p;
if (!penalizations.TryGetValue(penalizing_edge, out p))
{
p = 1;
}
else
{
p++;
}
penalizations[penalizing_edge] = p;
// evaluate or set tau.
if (tau > double.MinValue)
{ // evaluate if penalizations should end.
if (tau <= lambda * total_p)
{ // the penalization should end!
break;
}
}
else
{ // first edge being penalized.
tau = lambda * problem.WeightMatrix[penalizing_edge.From][penalizing_edge.To] / 10;
}
}
}
}
}
}
return original_solution;
}
/// <summary>
/// Executes a solver procedure.
/// </summary>
/// <param name="problem"></param>
/// <returns></returns>
internal override MaxTimeSolution Solve(MaxTimeProblem problem)
{
// _customers = problem.Customers;
//float[] solutions = OsmSharp.Math.VRP.Core.BestPlacement.CheapestInsertionHelper.CalculateBestValues(
// problem, _customers);
generations = 0;
_max_generations = 10000000;
// calculate one tsp solution.
//Tools.Math.TSP.ISolver tsp_solver = new OsmSharp.Math.TSP.EdgeAssemblyGenetic.EdgeAssemblyCrossOverSolver(_population, _stagnation,
// new OsmSharp.Math.TSP.Genetic.Solver.Operations.Generation._3OptGenerationOperation(),
// new OsmSharp.Math.TSP.Genetic.Solver.Operations.CrossOver.EdgeAssemblyCrossover(30,
// OsmSharp.Math.TSP.Genetic.Solver.Operations.CrossOver.EdgeAssemblyCrossover.EdgeAssemblyCrossoverSelectionStrategyEnum.SingleRandom,
// true));
//IRoute tsp_solution = tsp_solver.Solve(new OsmSharp.Routing.VRP.NoDepot.MaxTime.TSPPlacement.TSPProblem(
// problem));
// initialize the generation.
IGenerationOperation<MaxTimeSolution, MaxTimeProblem, Fitness> generation =
//new SolverGenerationOperation(new TSPPlacement.TSPPlacementSolver<ResolvedType>(
// this.Router, this.Max, this.DeliveryTime, tsp_solution));
new OsmSharp.Routing.VRP.NoDepot.MaxTime.Genetic.Generation.RandomBestPlacement();
//new SolverGenerationOperation(new CheapestInsertionSolverWithImprovements<ResolvedType>(
// this.Router, this.Max, this.DeliveryTime, 5, 0.1f, true, 0.1f, false, 1f, null, null));
//new SolverGenerationOperation(new CheapestInsertionSolverWithImprovements<ResolvedType>(
// this.Router, this.Max, this.DeliveryTime, 5, 0.1f, true, 0.1f, true, 1f));
// initialize the crossover.
ICrossOverOperation<MaxTimeSolution, MaxTimeProblem, Fitness> cross_over =
new OsmSharp.Routing.VRP.NoDepot.MaxTime.Genetic.CrossOver.RouteExchangeOperation();
// initialize the mutation.
//IMutationOperation<MaxTimeSolution, MaxTimeProblem, Fitness> mutation =
// new VehicleMutation();
List<IMutationOperation<MaxTimeSolution, MaxTimeProblem, Fitness>> mutators =
new List<IMutationOperation<MaxTimeSolution, MaxTimeProblem, Fitness>>();
mutators.Add(new VehicleMutation());
//mutators.Add(new ThreeOptMutation());
//mutators.Add(new RedivideRouteMutation());
mutators.Add(new RoutePartExchangeMutation());
if (_probabilities == null)
{
_probabilities = new List<double>();
_probabilities.Add(0.2);
_probabilities.Add(0.6);
_probabilities.Add(0.2);
}
CombinedMutation<MaxTimeSolution, MaxTimeProblem, Fitness> mutation = new CombinedMutation<MaxTimeSolution, MaxTimeProblem, Fitness>(
StaticRandomGenerator.Get(),
mutators,
_probabilities);
SolverSettings settings = new SolverSettings(_stagnation, _population, _max_generations,
_elitism_percentage, _cross_percentage, _mutation_percentage);
MaxTimeProblem genetic_problem = problem;// new MaxTimeProblem(max, problem, solutions);
Solver<MaxTimeSolution, MaxTimeProblem, Fitness> solver =
new Solver<MaxTimeSolution, MaxTimeProblem, Fitness>(genetic_problem, settings,
new TournamentBasedSelector<MaxTimeSolution, MaxTimeProblem, Fitness>(5, 0.5),
mutation, //new ThreeOptMutation(),
cross_over, // new RouteExchangeOperation(), //new RouteExchangeOperation(), //new RouteExchangeAndVehicleOperation(), // Order1CrossoverOperation()
generation, //new RandomBestPlacement(),//new RandomGeneration(), //new RandomBestPlacement(),
new FitnessCalculator());
solver.NewFittest += new Solver<MaxTimeSolution, MaxTimeProblem, Fitness>.NewFittestDelegate(solver_NewFittest);
//solver.NewGeneration += new Solver<MaxTimeSolution, Problem, Fitness>.NewGenerationDelegate(solver_NewGeneration);
Individual<MaxTimeSolution, MaxTimeProblem, Fitness> solution = solver.Start(null);
//this.solver_NewFittest(solution);
MaxTimeSolution routes = solution.Genomes;
long ticks_after = DateTime.Now.Ticks;
StringBuilder sizes = new StringBuilder();
foreach (int size in routes.Sizes)
{
sizes.Append(size);
sizes.Append(" ");
}
StringBuilder weights = new StringBuilder();
foreach (double weight in solution.Fitness.Weights)
{
weights.Append(weight.ToString(CultureInfo.InvariantCulture));
weights.Append(" ");
}
return routes;
}
