Error: int object is not iterable, how to resolve this?

Question

def update_basis(A, basis, i, j):
    for k, var in enumerate(basis):
        idx = int(var[1:])
        if A[i][j] == 1:
            basis[k] = "x" + str(j+1)
            break
    return basis

I wrote the above code, and I am getting error as stated. I even tried range(enumerate(basis)), after reading one of the answers here. That too doesn't seem to work. How do I get around this? PS. I took this code from - https://github.com/pyaf/operations-research/blob/master/simplex-method/utils.py I know there are many similar questions on this, but I just cant get one that answers me problem.

Full traceback error:
TypeError                                 Traceback (most recent call last)
<ipython-input-7-9809e74f4f64> in <module>
    120     print("\nIteration number : %d" % iter_num)
    121     #updating basis as variables enter and leave
--> 122     basis= update_basis(i,j,basis,nonbasic)
    123     #updating table
    124     A,b,c= row_operations(A,b,c,i,j)

<ipython-input-7-9809e74f4f64> in update_basis(A, basis, i, j)
     76 
     77 def update_basis(A, basis, i, j):
---> 78     for k, var in enumerate(basis):
     79         idx = int(var[1:])
     80         if A[i][j] == 1:

TypeError: 'int' object is not iterable

Please [edit] your code to expand it to a [mcve], and include the full traceback. — MisterMiyagi, Jan 14 '21 at 14:08
You are passing an `int` as `basis`, and the code wants something iterable. You need to look to where you use this function. — molbdnilo, Jan 14 '21 at 14:09
What is the point of ``var`` and ``idx``? They appear unused for calculating the result. — MisterMiyagi, Jan 14 '21 at 14:10
Please add the COMPLETE traceback of the error you are getting. — TheEagle, Jan 14 '21 at 14:25
Please take the time to read the [mcve] help page. The point is to provide a *minimal* example, not to dump more than 100 lines of code, many of which are dead. — MisterMiyagi, Jan 14 '21 at 14:47

TheEagle · Answer 1 · 2021-01-14T14:45:27.723

0

Your update_basis function is defined in https://github.com/pyaf/operations-research/blob/master/simplex-method/utils.py, and then used in https://github.com/pyaf/operations-research/blob/master/simplex-method/simplex.py, where one can see that basis is expected to be an array / list. So, the error will disappear if you pass a list as second argument, instead of a number.
EDIT: I think now that this

basis = update_basis(i, j, basis, nonbasic)

is your problem. You mixed up the order of the arguments. In the function definition, they are like this:

def update_basis(A, basis, i, j):

So, it should work if you change line 122 to:

basis = update_basis(nonbasic, basis, i, j)

edited Jan 14 '21 at 14:45

answered Jan 14 '21 at 14:18

TheEagle

5,808
3
11
39

Since that means ``var`` is an integer, ``var[1:]`` will fail. – MisterMiyagi Jan 14 '21 at 14:19
But..i did define basis as an array – huy Jan 14 '21 at 14:35
@huy please add your complete code until the line 122 – TheEagle Jan 14 '21 at 14:39
Be aware the function shown is similar but not equal to the ``simplex-method.utils. update_basis`` function. – MisterMiyagi Jan 14 '21 at 14:40
@huy edited my answer, but i think MisterMiyagis one is better – TheEagle Jan 14 '21 at 14:46

score 0 · Answer 2 · answered Jan 14 '21 at 14:20

0

The reason you get this error is because the function update_basis is called with the incorrect signature. Somewhere in this code (which you will see in the error message), an int is passed as the basis parameter, when this in fact should be an iterable collection. The problem is not in the function itself, but rather where it is called.

So to solve it, find where the function is called that produces this error and correct the argument

answered Jan 14 '21 at 14:20

Marksverdhei

31
1
1

could you look at the entire code once? because I'm not able to see the error – huy Jan 14 '21 at 14:33
Look at @MisterMiyagi 's answer. Instead of calling it with `update_basis(i,j,basis,nonbasic)` you should probaly call it with this way: `update_basis(nonbasic, basis, i,j)` – Marksverdhei Jan 14 '21 at 14:50

Error: int object is not iterable, how to resolve this?

2 Answers2