问题
I have tried to implements start and end locations for routes on VRPTW example following ufficial guide of ortools.
in data, i have add:
data['starts'] = [1, 2, 15, 16]
data['ends'] = [0, 0, 0, 0]
And i have changed RoutingIndexManager to:
# Create the routing index manager.
manager = pywrapcp.RoutingIndexManager(
len(data['distance_matrix']), data['num_vehicles'], data['starts'],
data['ends'])
This is my code after join that instruction with original VRPTW example:
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['time_matrix'] = [
[0, 6, 9, 8, 7, 3, 6, 2, 3, 2, 6, 6, 4, 4, 5, 9, 7],
[6, 0, 8, 3, 2, 6, 8, 4, 8, 8, 13, 7, 5, 8, 12, 10, 14],
[9, 8, 0, 11, 10, 6, 3, 9, 5, 8, 4, 15, 14, 13, 9, 18, 9],
[8, 3, 11, 0, 1, 7, 10, 6, 10, 10, 14, 6, 7, 9, 14, 6, 16],
[7, 2, 10, 1, 0, 6, 9, 4, 8, 9, 13, 4, 6, 8, 12, 8, 14],
[3, 6, 6, 7, 6, 0, 2, 3, 2, 2, 7, 9, 7, 7, 6, 12, 8],
[6, 8, 3, 10, 9, 2, 0, 6, 2, 5, 4, 12, 10, 10, 6, 15, 5],
[2, 4, 9, 6, 4, 3, 6, 0, 4, 4, 8, 5, 4, 3, 7, 8, 10],
[3, 8, 5, 10, 8, 2, 2, 4, 0, 3, 4, 9, 8, 7, 3, 13, 6],
[2, 8, 8, 10, 9, 2, 5, 4, 3, 0, 4, 6, 5, 4, 3, 9, 5],
[6, 13, 4, 14, 13, 7, 4, 8, 4, 4, 0, 10, 9, 8, 4, 13, 4],
[6, 7, 15, 6, 4, 9, 12, 5, 9, 6, 10, 0, 1, 3, 7, 3, 10],
[4, 5, 14, 7, 6, 7, 10, 4, 8, 5, 9, 1, 0, 2, 6, 4, 8],
[4, 8, 13, 9, 8, 7, 10, 3, 7, 4, 8, 3, 2, 0, 4, 5, 6],
[5, 12, 9, 14, 12, 6, 6, 7, 3, 3, 4, 7, 6, 4, 0, 9, 2],
[9, 10, 18, 6, 8, 12, 15, 8, 13, 9, 13, 3, 4, 5, 9, 0, 9],
[7, 14, 9, 16, 14, 8, 5, 10, 6, 5, 4, 10, 8, 6, 2, 9, 0],
]
data['time_windows'] = [
(0, 5), # depot
(7, 12), # 1
(10, 15), # 2
(16, 18), # 3
(10, 13), # 4
(0, 5), # 5
(5, 10), # 6
(0, 4), # 7
(5, 10), # 8
(0, 3), # 9
(10, 16), # 10
(10, 15), # 11
(0, 5), # 12
(5, 10), # 13
(7, 8), # 14
(10, 15), # 15
(11, 15), # 16
]
data['num_vehicles'] = 4
data['starts'] = [0, 2, 0, 0]
data['ends'] = [1, 0, 0, 0]
return data
def print_solution(data, manager, routing, assignment):
"""Prints assignment on console."""
time_dimension = routing.GetDimensionOrDie('Time')
total_time = 0
for vehicle_id in range(data['num_vehicles']):
index = routing.Start(vehicle_id)
plan_output = 'Route for vehicle {}:\n'.format(vehicle_id)
while not routing.IsEnd(index):
time_var = time_dimension.CumulVar(index)
plan_output += '{0} Time({1},{2}) -> '.format(
manager.IndexToNode(index), assignment.Min(time_var),
assignment.Max(time_var))
index = assignment.Value(routing.NextVar(index))
time_var = time_dimension.CumulVar(index)
plan_output += '{0} Time({1},{2})\n'.format(
manager.IndexToNode(index), assignment.Min(time_var),
assignment.Max(time_var))
plan_output += 'Time of the route: {}min\n'.format(
assignment.Min(time_var))
print(plan_output)
total_time += assignment.Min(time_var)
print('Total time of all routes: {}min'.format(total_time))
def main():
"""Solve the VRP with time windows."""
data = create_data_model()
manager = pywrapcp.RoutingIndexManager(
len(data['time_matrix']), data['num_vehicles'], data['starts'], data['ends'])
routing = pywrapcp.RoutingModel(manager)
def time_callback(from_index, to_index):
"""Returns the travel time between the two nodes."""
# Convert from routing variable Index to time matrix NodeIndex.
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(time_callback)
routing.SetArcCostEvaluatorOfAllVehicles(transit_callback_index)
time = 'Time'
routing.AddDimension(
transit_callback_index,
30, # allow waiting time
30, # maximum time per vehicle
False, # Don't force start cumul to zero.
time)
time_dimension = routing.GetDimensionOrDie(time)
# Add time window constraints for each location except depot.
for location_idx, time_window in enumerate(data['time_windows']):
if location_idx == 0:
continue
index = manager.NodeToIndex(location_idx)
time_dimension.CumulVar(index).SetRange(time_window[0], time_window[1])
# Add time window constraints for each vehicle start node.
for vehicle_id in range(data['num_vehicles']):
index = routing.Start(vehicle_id)
time_dimension.CumulVar(index).SetRange(data['time_windows'][0][0],
data['time_windows'][0][1])
for i in range(data['num_vehicles']):
routing.AddVariableMinimizedByFinalizer(
time_dimension.CumulVar(routing.Start(i)))
routing.AddVariableMinimizedByFinalizer(
time_dimension.CumulVar(routing.End(i)))
search_parameters = pywrapcp.DefaultRoutingSearchParameters()
search_parameters.first_solution_strategy = (
routing_enums_pb2.FirstSolutionStrategy.PATH_CHEAPEST_ARC)
assignment = routing.SolveWithParameters(search_parameters)
if assignment:
print_solution(data, manager, routing, assignment)
if __name__ == '__main__':
main()
Now, if i try to execute code, python exit with following error: Process finished with exit code -1073741819 (0xC0000005)
I have tried to isolate bug, and seem to be related with time window constraints for each location except depot.
If i remove:
time_dimension.CumulVar(index).SetRange(time_window[0], time_window[1])
Code works without errors, but obviously without time windows constraints.
I don't understood where is the problem and how to solve. Can you help me?
回答1:
have you tried set "maximum time per vehicle" to a larger value? Like in documentation.
来源：https://stackoverflow.com/questions/56283053/google-ortools-vrptw-with-start-and-end-locations-for-routes