TypeError: unsupported operand type(s) for -: 'bool' and 'NoneType'

[zuhal kartal]

Hi everyone,

I defined a variable with four indices in my model which is g[i][j][k][l].

When I try to add a constraint as in the following:

for i in N:
    for j in N:
        if i != j:
            for k in N:
                for l in N[:k]:
                    m.addConstr(g[i][j][k][l] == g[j][i][l][k])

I got the TypeError: unsupported operand type(s) for -: 'bool' and 'NoneType'.

If you have any idea, where the problem stems from, could you please share it with me?

Thank you in advance from now on,

Zuhal.

[Renan Garcia]

You should verify that the objects stored in g[i][j][k][l] and g[j][i][k][l] are of type Var or LinExpr for all i, j, k and l. This error indicates that at least one is of type bool or None.

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[zuhal kartal]

Thank you so much Renan,

I've just solved the problem.

Zuhal.

21 Kasım 2016 Pazartesi 16:47:18 UTC+2 tarihinde Renan Garcia yazdı:

[Shirin Naj]

Hi I have the same problem and I couldnt solve it..how can I define Var or LinExpr for all i?

my code is: 

 for i in range(clients):

            T[i] = model.addVar(lb=1, ub=1440,name='T[%s]' % ( i))            

for i in range(clients):

           model.addConstr(start_times[i] <= T[i])

THE ERROR IS:

Traceback (most recent call last):

  File "c:\Users\Admin\Desktop\SampleToolBox\Python\cvrp_model.py", line 2, in <module>

    import math

  File "C:\sh\Lib\site-packages\gurobipy\gurobipy.pyd", line 2466, in gurobipy.Model.addConstr (../../src/python/gurobipy.c:77325)

[Renan Garcia]

It appears that start_times (not T) is the issue here. You should verify that the object stored in start_times[i] is valid for all i. This error indicates that at least one is of type bool or None.

[Shirin Naj]

Thanks :)

[chuyu...@gmail.com]

Hi,

I have the same problem. How do you fix it?

[Kostja Siefen]

Please make sure that all elements of your expression have a proper type. 

To debug this, you can add a check for None values before creating the expression, for example

for i in range(clients):

    if start_times[i] is None or T[i] is None)

        print("Invalid values for index %d!" % i)

    else:

        model.addConstr(start_times[i] <= T[i])

Kostja