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- from __future__ import print_function
- from ortools.constraint_solver import routing_enums_pb2
- from ortools.constraint_solver import pywrapcp
- def create_data_model():
- """Stores the data for the problem."""
- data = {}
- data['distance_matrix'] = [
- [
- 0, 548, 776, 696, 582, 274, 502, 194, 308, 194, 536, 502, 388, 354,
- 468, 776, 662
- ],
- [
- 548, 0, 684, 308, 194, 502, 730, 354, 696, 742, 1084, 594, 480, 674,
- 1016, 868, 1210
- ],
- [
- 776, 684, 0, 992, 878, 502, 274, 810, 468, 742, 400, 1278, 1164,
- 1130, 788, 1552, 754
- ],
- [
- 696, 308, 992, 0, 114, 650, 878, 502, 844, 890, 1232, 514, 628, 822,
- 1164, 560, 1358
- ],
- [
- 582, 194, 878, 114, 0, 536, 764, 388, 730, 776, 1118, 400, 514, 708,
- 1050, 674, 1244
- ],
- [
- 274, 502, 502, 650, 536, 0, 228, 308, 194, 240, 582, 776, 662, 628,
- 514, 1050, 708
- ],
- [
- 502, 730, 274, 878, 764, 228, 0, 536, 194, 468, 354, 1004, 890, 856,
- 514, 1278, 480
- ],
- [
- 194, 354, 810, 502, 388, 308, 536, 0, 342, 388, 730, 468, 354, 320,
- 662, 742, 856
- ],
- [
- 308, 696, 468, 844, 730, 194, 194, 342, 0, 274, 388, 810, 696, 662,
- 320, 1084, 514
- ],
- [
- 194, 742, 742, 890, 776, 240, 468, 388, 274, 0, 342, 536, 422, 388,
- 274, 810, 468
- ],
- [
- 536, 1084, 400, 1232, 1118, 582, 354, 730, 388, 342, 0, 878, 764,
- 730, 388, 1152, 354
- ],
- [
- 502, 594, 1278, 514, 400, 776, 1004, 468, 810, 536, 878, 0, 114,
- 308, 650, 274, 844
- ],
- [
- 388, 480, 1164, 628, 514, 662, 890, 354, 696, 422, 764, 114, 0, 194,
- 536, 388, 730
- ],
- [
- 354, 674, 1130, 822, 708, 628, 856, 320, 662, 388, 730, 308, 194, 0,
- 342, 422, 536
- ],
- [
- 468, 1016, 788, 1164, 1050, 514, 514, 662, 320, 274, 388, 650, 536,
- 342, 0, 764, 194
- ],
- [
- 776, 868, 1552, 560, 674, 1050, 1278, 742, 1084, 810, 1152, 274,
- 388, 422, 764, 0, 798
- ],
- [
- 662, 1210, 754, 1358, 1244, 708, 480, 856, 514, 468, 354, 844, 730,
- 536, 194, 798, 0
- ],
- ]
- data['demands'] = [0, 1, 1, 2, 4, 2, 4, 8, 8, 1, 2, 1, 2, 4, 4, 8, 8]
- data['pickups_deliveries'] = [
- [1, 6],
- [2, 10],
- [4, 3],
- [5, 9],
- [7, 8],
- [15, 11],
- [13, 12],
- [16, 14],
- ]
- data['vehicle_capacities'] = [15, 15, 15, 15]
- data['num_vehicles'] = 4
- data['depot'] = 0
- return data
- def print_solution(data, manager, routing, assignment):
- """Prints assignment on console."""
- total_distance = 0
- for vehicle_id in range(data['num_vehicles']):
- index = routing.Start(vehicle_id)
- plan_output = 'Route for vehicle {}:\n'.format(vehicle_id)
- route_distance = 0
- while not routing.IsEnd(index):
- plan_output += ' {} -> '.format(manager.IndexToNode(index))
- previous_index = index
- index = assignment.Value(routing.NextVar(index))
- route_distance += routing.GetArcCostForVehicle(
- previous_index, index, vehicle_id)
- plan_output += '{}\n'.format(manager.IndexToNode(index))
- plan_output += 'Distance of the route: {}m\n'.format(route_distance)
- print(plan_output)
- total_distance += route_distance
- print('Total Distance of all routes: {}m'.format(total_distance))
- def main():
- # Instantiate the data problem.
- data = create_data_model()
- # Create the routing index manager.
- manager = pywrapcp.RoutingIndexManager(len(data['distance_matrix']), data['num_vehicles'], data['depot'])
- # Create Routing Model.
- routing = pywrapcp.RoutingModel(manager)
- # Create and register a transit callback.
- def distance_callback(from_index, to_index):
- """Returns the distance between the two nodes."""
- # Convert from routing variable Index to distance matrix NodeIndex.
- from_node = manager.IndexToNode(from_index)
- to_node = manager.IndexToNode(to_index)
- return data['distance_matrix'][from_node][to_node]
- transit_callback_index = routing.RegisterTransitCallback(distance_callback)
- routing.SetArcCostEvaluatorOfAllVehicles(transit_callback_index)
- # Add Distance constraint.
- dimension_name = 'Distance'
- routing.AddDimension(
- transit_callback_index,
- 0, # no slack
- 3000, # vehicle maximum travel distance
- True, # start cumul to zero
- dimension_name)
- distance_dimension = routing.GetDimensionOrDie(dimension_name)
- distance_dimension.SetGlobalSpanCostCoefficient(100)
- # Add Capacity constraint.
- def demand_callback(from_index):
- """Returns the demand of the node."""
- # Convert from routing variable Index to demands NodeIndex.
- from_node = manager.IndexToNode(from_index)
- return data['demands'][from_node]
- demand_callback_index = routing.RegisterUnaryTransitCallback(demand_callback)
- routing.AddDimensionWithVehicleCapacity(
- demand_callback_index,
- 0, # null capacity slack
- data['vehicle_capacities'], # vehicle maximum capacities
- True, # start cumul to zero
- 'Capacity')
- # Define Transportation Requests.
- for request in data['pickups_deliveries']:
- pickup_index = manager.NodeToIndex(request[0])
- delivery_index = manager.NodeToIndex(request[1])
- routing.AddPickupAndDelivery(pickup_index, delivery_index)
- routing.solver().Add(routing.VehicleVar(pickup_index) == routing.VehicleVar(delivery_index))
- routing.solver().Add(distance_dimension.CumulVar(pickup_index) <= distance_dimension.CumulVar(delivery_index))
- # Setting first solution heuristic.
- search_parameters = pywrapcp.DefaultRoutingSearchParameters()
- search_parameters.first_solution_strategy = (routing_enums_pb2.FirstSolutionStrategy.PATH_CHEAPEST_ARC)
- search_parameters.solution_limit = 1
- # search_parameters.time_limit.seconds = 300
- # Solve the problem.
- assignment = routing.SolveWithParameters(search_parameters)
- # Print solution on console.
- if assignment:
- print_solution(data, manager, routing, assignment)
- if __name__ == '__main__':
- main()
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