This example covers:
- defining and creating different 'depots', vehicles and their types
- defining a problem with finite fleet-size
- reading and creating an algorithm
- plotting the solution
It is based on the problem instance P08 defined by
Cordeau, J.-F., Gendreau, M. and Laporte, G. (1997), A tabu search heuristic for periodic and multi-depot vehicle routing problems. Networks, 30: 105–119.
Please visit for example this site to get more information on Multiple Depot VRP.
Before you start, [add the latest release to your pom](https://github.com/jsprit/jsprit/wiki/Add-latest-release-to-your-pom). Additionally, create an output folder in your project directory. Either do it manually or add the following lines to your code:
File dir = new File("output");
// if the directory does not exist, create it
if (!dir.exists()){
System.out.println("creating directory ./output");
boolean result = dir.mkdir();
if(result) System.out.println("./output created");
}
All services of P08 are stored in an xml-file called vrp_cordeau_08.xml (you can find it [here](https://github.com/jsprit/jsprit/tree/master/jsprit-examples/input)). You read them into your problemBuilder as follows
VehicleRoutingProblem.Builder vrpBuilder = VehicleRoutingProblem.Builder.newInstance();
/*
* Read cordeau-instance p08, BUT only its services without any vehicles
*/
new VrpXMLReader(vrpBuilder).read("input/vrp_cordeau_08.xml");
Define depots and vehicles:
/*
* add vehicles with its depots
* 2 depots with the following coordinates:
* (-33,33), (33,-33)
*
* each with 14 vehicles each with a capacity of 500 and a maximum duration of 310
*/
int nuOfVehicles = 14;
int capacity = 500;
double maxDuration = 310;
Coordinate firstDepotCoord = Coordinate.newInstance(-33, 33);
Coordinate second = Coordinate.newInstance(33, -33);
int depotCounter = 1;
for(Coordinate depotCoord : Arrays.asList(firstDepotCoord,second)){
for(int i=0;i<nuOfVehicles;i++){
String typeId = depotCounter + "_type";
VehicleType vehicleType = VehicleTypeImpl.Builder.newInstance(typeId).addCapacityDimension(0,capacity).setCostPerDistance(1.0).build();
String vehicleId = depotCounter + "_" + (i+1) + "_vehicle";
VehicleImpl.VehicleBuilder vehicleBuilder = VehicleImpl.Builder.newInstance(vehicleId);
vehicleBuilder.setStartLocation(depotCoord); //defines the location of the vehicle and thus the depot
vehicleBuilder.setType(vehicleType)
vehicleBuilder.setLatestArrival(maxDuration);
Vehicle vehicle = vehicleBuilder.build();
vrpBuilder.addVehicle(vehicle);
}
depotCounter++;
}
Build the problem, and define and run an algorithm like this:
/*
* define problem with finite fleet
*/
vrpBuilder.setFleetSize(FleetSize.FINITE);
/*
* build the problem
*/
VehicleRoutingProblem vrp = vrpBuilder.build();
/*
* solve the problem
*/
VehicleRoutingAlgorithm vra = VehicleRoutingAlgorithms.readAndCreateAlgorithm(vrp,"input/algorithmConfig.xml");
Collection solutions = vra.searchSolutions();
The problem will be looking like this:
Running this algorithm yields to the following solution:
You can find the entire code here.