Pickup Delivery VRP on Python Error with routing.solver

[Thuc Nguyen Canh]

Hello,

I got below error:

Traceback (most recent call last):

  File "examples/python/pdvrp.py", line 101, in <module>

    app.run()

  File "/usr/local/lib/python2.7/dist-packages/google/apputils/app.py", line 238, in run

    return _actual_start()

  File "/usr/local/lib/python2.7/dist-packages/google/apputils/app.py", line 267, in _actual_start

    really_start()

  File "/usr/local/lib/python2.7/dist-packages/google/apputils/app.py", line 220, in really_start

    sys.exit(main(argv))

  File "examples/python/pdvrp.py", line 77, in main

    solver.AddConstraint(solver.MakeEquality(routing.VehicleVar(routing.NodeToIndex(7)),routing.VehicleVar(routing.NodeToIndex(8))))

  File "/usr/local/lib/python2.7/dist-packages/ortools-3.3629-py2.7-linux-x86_64.egg/ortools/constraint_solver/pywrapcp.py", line 242, in <lambda>

    __getattr__ = lambda self, name: _swig_getattr(self, Solver, name)

  File "/usr/local/lib/python2.7/dist-packages/ortools-3.3629-py2.7-linux-x86_64.egg/ortools/constraint_solver/pywrapcp.py", line 74, in _swig_getattr

    return _swig_getattr_nondynamic(self, class_type, name, 0)

  File "/usr/local/lib/python2.7/dist-packages/ortools-3.3629-py2.7-linux-x86_64.egg/ortools/constraint_solver/pywrapcp.py", line 69, in _swig_getattr_nondynamic

    return object.__getattr__(self, name)

AttributeError: type object 'object' has no attribute '__getattr__'

Here is my code:

    routing = pywrapcp.RoutingModel(tsp_size, 1)

    routing.SetDepot(10);

    search_parameters = pywrapcp.RoutingModel.DefaultSearchParameters()

    # Setting first solution heuristic: the

    # method for finding a first solution to the problem.

    search_parameters.first_solution_strategy = (

        routing_enums_pb2.FirstSolutionStrategy.PATH_CHEAPEST_ARC)

    # Create the distance callback, which takes two arguments (the from and to node indices)

    # and returns the distance between these nodes.

    dist_between_nodes = CreateDistanceCallback()

    dist_callback = dist_between_nodes.Distance

    routing.SetArcCostEvaluatorOfAllVehicles(dist_callback)

    solver = routing.solver()

    solver.AddConstraint(solver.MakeEquality(routing.VehicleVar(routing.NodeToIndex(7)),routing.VehicleVar(routing.NodeToIndex(8))))

    routing.AddPickupAndDelivery(7,8)

As I am a python newbie, so I dont know what the error is. Please help. Thanks

[Driss Lahlou]

Hello Thuc,

First of all, you're using an old version of ortools (3.3629), so you should update to the latest version like so : 

easy_install --user -U ortools

In case python keeps using the old version, please remove it manually, or using "pip uninstall".

Then you should add a constraint to your model using Add() method as shown in the guide.

I hope this helps.

--

Driss

[Driss Lahlou]

Addendum :

The previous link to the guide is wrong. Please use this one for examples of adding constraints to the solver.

[Thuc Nguyen Canh]

You saved my day, thank you Driss.

Thuc

Vào 23:51:34 UTC+7 Thứ Tư, ngày 10 tháng 8 năm 2016, Driss Lahlou đã viết:

[Driss Lahlou]

You are welcome.

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Regards,

driss

[Daniel Merchán]

Hi - I have been trying to find the 'pdvrp.py' script. Does anyone know where to find it?

Thanks

- DM

[Jon Orwant]

I believe that's simply the name Thuc Nguyen Canh gave to the program he's working on.

https://developers.google.com/optimization/routing/tsp/vehicle_routing_time_windows should help you.

Jon

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