public void Init()
{
if (DataModel != null)
{
// Create RoutingModel Index RoutingIndexManager
if (DataModel.Starts != null && DataModel.Ends != null)
{
RoutingIndexManager = new RoutingIndexManager(
DataModel.TravelTimes.GetLength(0),
DataModel.VehicleCapacities.Length,
DataModel.Starts, DataModel.Ends);
}
else
{
throw new Exception("Starts or Ends in DataModel is null");
}
//Create routing model
RoutingModel = new RoutingModel(RoutingIndexManager);
// Create and register a transit callback.
var transitCallbackIndex = RoutingModel.RegisterTransitCallback(
(long fromIndex, long toIndex) =>
{
// Convert from routing variable Index to time matrix or distance matrix NodeIndex.
var fromNode = RoutingIndexManager.IndexToNode(fromIndex);
var toNode = RoutingIndexManager.IndexToNode(toIndex);
return(DataModel.TravelTimes[fromNode, toNode]);
}
);
//Create and register demand callback
var demandCallbackIndex = RoutingModel.RegisterUnaryTransitCallback(
(long fromIndex) => {
// Convert from routing variable Index to demand NodeIndex.
var fromNode = RoutingIndexManager.IndexToNode(fromIndex);
return(DataModel.Demands[fromNode]);
}
);
if (DropNodesAllowed)
{
// Allow to drop nodes.
//The penalty should be larger than the sum of all travel times locations (excluding the depot).
//As a result, after dropping one location to make the problem feasible, the solver won't drop any additional locations,
//because the penalty for doing so would exceed any further reduction in travel time.
//If we want to make as many deliveries as possible, penalty value should be larger than the sum of all travel times between locations
long penalty = 99999999;
for (int j = 0; j < DataModel.Starts.GetLength(0); j++)
{
var startIndex = DataModel.Starts[j];
for (int i = 0; i < DataModel.TravelTimes.GetLength(0); ++i)
{
if (startIndex != i)
{
RoutingModel.AddDisjunction(new long[] { RoutingIndexManager.NodeToIndex(i) }, penalty);//adds disjunction to all stop besides start stops
}
}
}
}
var vehicleCost = 10000;
RoutingModel.SetFixedCostOfAllVehicles(vehicleCost); //adds a penalty for using each vehicle
RoutingModel.SetArcCostEvaluatorOfAllVehicles(transitCallbackIndex); //Sets the cost function of the model such that the cost of a segment of a route between node 'from' and 'to' is evaluator(from, to), whatever the route or vehicle performing the route.
//Adds capacity constraints
RoutingModel.AddDimensionWithVehicleCapacity(
demandCallbackIndex, 0, // null capacity slack
DataModel.VehicleCapacities, // vehicle maximum capacities
false, // start cumul to zero
"Capacity");
RoutingDimension capacityDimension = RoutingModel.GetMutableDimension("Capacity");
//Add Time window constraints
RoutingModel.AddDimension(
transitCallbackIndex, // transit callback
86400, // allow waiting time (24 hours in seconds)
86400, // maximum travel time per vehicle (24 hours in seconds)
DataModel.ForceCumulToZero, // start cumul to zero
"Time");
RoutingDimension timeDimension = RoutingModel.GetMutableDimension("Time");
//timeDimension.SetGlobalSpanCostCoefficient(10);
var solver = RoutingModel.solver();
// Add time window constraints for each location except depot.
for (int i = 0; i < DataModel.TimeWindows.GetLength(0); i++)
{
long index = RoutingIndexManager.NodeToIndex(i); //gets the node index
if (index != -1)
{
var lowerBound = DataModel.TimeWindows[i, 0]; //minimum time to be at current index (lower bound for the timeWindow of current Index)
var softUpperBound = DataModel.TimeWindows[i, 1]; //soft maxUpperBound for the timeWindow at current index
var upperBound = softUpperBound + MaximumDeliveryDelayTime; //maxUpperBound to be at current index (upperbound for the timeWindow at current index)
//softupperbound and upperbound are different because the upperbound is usually bigger than the softuppberbound in order to soften the current timeWindows, enabling to generate a solution that accomodates more requests
timeDimension.CumulVar(index).SetRange(lowerBound, upperBound); //sets the maximum upper bound and lower bound limit for the timeWindow at the current index
timeDimension.SetCumulVarSoftUpperBound(index, softUpperBound, 10000); //adds soft upper bound limit which is the requested time window
RoutingModel.AddToAssignment(timeDimension.SlackVar(index)); //add timeDimension slack var for current index to the assignment
RoutingModel.AddToAssignment(timeDimension.TransitVar(index)); // add timeDimension transit var for current index to the assignment
RoutingModel.AddToAssignment(capacityDimension.TransitVar(index)); //add transit capacity var for current index to assignment
}
}
// Add time window constraints for each vehicle start node, and add to assignment the slack and transit vars for both dimensions
for (int i = 0; i < DataModel.VehicleCapacities.Length; i++)
{
long index = RoutingModel.Start(i);
var startDepotIndex = DataModel.Starts[i];
timeDimension.CumulVar(index).SetRange(DataModel.TimeWindows[startDepotIndex, 0], DataModel.TimeWindows[startDepotIndex, 1]); //this guarantees that a vehicle must visit the location during its time
RoutingModel.AddToAssignment(timeDimension.SlackVar(index)); //add timeDimension slack var for depot index for vehicle i depotto assignment
RoutingModel.AddToAssignment(timeDimension.TransitVar(index)); //add timeDimension transit var for depot index for vehicle i depot to assignment
RoutingModel.AddToAssignment(capacityDimension.TransitVar(index)); //add capacityDimension transit var for vehicle i depot
}
//Add client max ride time constraint, enabling better service quality
for (int i = 0; i < DataModel.PickupsDeliveries.Length; i++) //iterates over each pickupDelivery pair
{
int vehicleIndex = -1;
if (DataModel.PickupsDeliveries[i][0] == -1) //if the pickupDelivery is a customer inside a vehicle
{
vehicleIndex = DataModel.CustomersVehicle[i]; //gets the vehicle index
}
var pickupIndex = vehicleIndex == -1 ? RoutingIndexManager.NodeToIndex(DataModel.PickupsDeliveries[i][0]):RoutingModel.Start(vehicleIndex); //if is a customer inside a vehicle the pickupIndex will be the vehicle startIndex, otherwise its the customers real pickupIndex
var deliveryIndex = RoutingIndexManager.NodeToIndex(DataModel.PickupsDeliveries[i][1]);
var rideTime = DataModel.CustomersRideTimes[i];
var directRideTimeDuration = DataModel.TravelTimes[pickupIndex, DataModel.PickupsDeliveries[i][1]];
var realRideTimeDuration = rideTime + (timeDimension.CumulVar(deliveryIndex) - timeDimension.CumulVar(pickupIndex)); //adds the currentRideTime of the customer and subtracts cumulative value of the ride time of the delivery index with the current one of the current index to get the real ride time duration
solver.Add(realRideTimeDuration < directRideTimeDuration + DataModel.MaxCustomerRideTime); //adds the constraint so that the current ride time duration does not exceed the directRideTimeDuration + maxCustomerRideTimeDuration
}
//Add precedence and same vehicle Constraints
for (int i = 0; i < DataModel.PickupsDeliveries.GetLength(0); i++)
{
if (DataModel.PickupsDeliveries[i][0] != -1)
{
long pickupIndex = RoutingIndexManager.NodeToIndex(DataModel.PickupsDeliveries[i][0]); //pickup index
long deliveryIndex = RoutingIndexManager.NodeToIndex(DataModel.PickupsDeliveries[i][1]); //delivery index
RoutingModel.AddPickupAndDelivery(pickupIndex, deliveryIndex); //Notifies that the pickupIndex and deliveryIndex form a pair of nodes which should belong to the same route.
solver.Add(solver.MakeEquality(RoutingModel.VehicleVar(pickupIndex), RoutingModel.VehicleVar(deliveryIndex))); //Adds a constraint to the solver, that defines that both these pickup and delivery pairs must be picked up and delivered by the same vehicle (same route)
solver.Add(solver.MakeLessOrEqual(timeDimension.CumulVar(pickupIndex), timeDimension.CumulVar(deliveryIndex))); //Adds the precedence constraint to the solver, which defines that each item must be picked up at pickup index before it is delivered to the delivery index
//timeDimension.SlackVar(pickupIndex).SetMin(4);//mininimum slack will be 3 seconds (customer enter timer)
//timeDimension.SlackVar(deliveryIndex).SetMin(3); //minimum slack will be 3 seconds (customer leave time)
}
}
//Constraints to enforce that if there is a customer inside a vehicle, it has to be served by that vehicle
for (int customerIndex = 0; customerIndex < DataModel.CustomersVehicle.GetLength(0); customerIndex++)
{
var vehicleIndex = DataModel.CustomersVehicle[customerIndex];
if (vehicleIndex != -1) //if the current customer is inside a vehicle
{
var vehicleStartIndex = RoutingModel.Start(vehicleIndex); //vehicle start depot index
var deliveryIndex = RoutingIndexManager.NodeToIndex(DataModel.PickupsDeliveries[customerIndex][1]); //gets the deliveryIndex
solver.Add(solver.MakeEquality(RoutingModel.VehicleVar(vehicleStartIndex), RoutingModel.VehicleVar(deliveryIndex))); //vehicle with vehicleIndex has to be the one that delivers customer with nodeDeliveryIndex;
//this constraint enforces that the vehicle indexed by vehicleIndex has to be the vehicle which services (goes to) the nodeDeliveryIndex as well
}
}
for (int i = 0; i < DataModel.VehicleCapacities.Length; i++)
{
RoutingModel.AddVariableMinimizedByFinalizer(
timeDimension.CumulVar(RoutingModel.Start(i)));
RoutingModel.AddVariableMinimizedByFinalizer(
timeDimension.CumulVar(RoutingModel.End(i)));
}
}
}