ORTools - vehicle routing -最大限度地减少途中的包裹时间

from ortools.constraint_solver import routing_enums_pb2
from ortools.constraint_solver import pywrapcp

def create_data_model():
    data = {}
    data['distance_matrix'] = [
        [0, 500, 100, 200],
        [500, 0, 800, 600],
        [100, 800, 0, 300],
        [200, 600, 300, 0]
    ]
    data['time_matrix'] = [
        [0, 10, 20, 30],
        [10, 0, 50, 40],
        [20, 50, 0, 60],
        [30, 40, 60, 0]
    ]
    data['num_vehicles'] = 1
    data['depot'] = 0
    return data

def main():
    data = create_data_model()
    manager = pywrapcp.RoutingIndexManager(len(data['distance_matrix']), data['num_vehicles'], data['depot'])
    routing = pywrapcp.RoutingModel(manager)

    def distance_callback(from_index, to_index):
        from_node = manager.IndexToNode(from_index)
        to_node = manager.IndexToNode(to_index)
        return data['distance_matrix'][from_node][to_node]

    def time_callback(from_index, to_index):
        from_node = manager.IndexToNode(from_index)
        to_node = manager.IndexToNode(to_index)
        return data['time_matrix'][from_node][to_node]

    transit_callback_index = routing.RegisterTransitCallback(distance_callback)
    routing.SetArcCostEvaluatorOfAllVehicles(transit_callback_index)

    transit_time_callback_index = routing.RegisterTransitCallback(time_callback)
    routing.AddDimension(transit_time_callback_index,  # transit callback index
                         0,  # no slack
                         1000,  # maximum time per vehicle
                         True,  # start cumul to zero
                         'Time')
    routing.SetArcCostEvaluatorOfAllVehicles(transit_time_callback_index)

    search_parameters = pywrapcp.DefaultRoutingSearchParameters()
    search_parameters.first_solution_strategy = (
        routing_enums_pb2.FirstSolutionStrategy.PATH_CHEAPEST_ARC)

    solution = routing.SolveWithParameters(search_parameters)
    if solution:
        print_solution(manager, routing, solution)

def print_solution(manager, routing, solution):
    print(f'Objective: {solution.ObjectiveValue()}')
    index = routing.Start(0)
    plan_output = 'Route for vehicle 0:\n'
    route_distance = 0
    while not routing.IsEnd(index):
        plan_output += f' {manager.IndexToNode(index)} -> '
        previous_index = index
        index = solution.Value(routing.NextVar(index))
        route_distance += routing.GetArcCostForVehicle(previous_index, index, 0)
    plan_output += f'{manager.IndexToNode(index)}\n'
    route_time = solution.Minutes(routing.GetTotalTimeDimension().CumulVar(index))
    print(f'Time of the route: {route_time} min\n')
    print(plan_output)

if __name__ == '__main__':
    main()