I'm using the PyMathProg package. Documentation can be found here: http://pymprog.sourceforge.net/.
I've created a basic MIP program, but I'm running into a syntax issue with my constraints. I followed the dive-in tutorial in the documentation above and then modified.
from pymprog import *
a = (1, 1, 1, 1, 1, 1, 1, 1, 1, 1)
b = (10, 20, 30, 40, 50, 60, 70, 80, 90, 100)
c = (1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
d = (5, 10, 15, 20, 25, 30, 35, 40, 45, 50)
s = (2, 8, 5, 4, 6, 1, 4, 3, 8, 10)
begin('example')
verbose(True)
x = var('x', 10, kind=bool)
maximize(sum(s[i]*x[i] for i in range(10)))
for i in range(10):
sum(x[i]) == 5
sum(a[i]*x[i]) >= 5
sum(b[i]*x[i]) >= 250
sum(c[i]*x[i]) >= 15
sum(d[i]*x[i]) >= 90
solve()
I'm not sure why I'm getting the error below.
sum(x[i]) == 5
TypeError: '_var' object is not iterable
You're using sum, which is fine. It takes a list and adds them up
sum([1,2,3])
6
The problem is, you're passing into it something that isn't a list, x[i] and the others, they are single elements.
This is why it says TypeError: '_var' object is not iterable. Because you are passing in elements from the list x, that is created by using var.
I thing what you're trying to do is something like this:
from pymprog import *
a = (1, 1, 1, 1, 1, 1, 1, 1, 1, 1)
b = (10, 20, 30, 40, 50, 60, 70, 80, 90, 100)
c = (1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
d = (5, 10, 15, 20, 25, 30, 35, 40, 45, 50)
s = (2, 8, 5, 4, 6, 1, 4, 3, 8, 10)
begin('example')
verbose(True)
x = var('x', 10, kind=bool)
maximize(sum(s[i]*x[i] for i in range(10)))
for i in range(10):
sum(x[j+i] for j in range(3)) == 5
sum(a[i]*x[j] for j in range(3)) >= 5
sum(b[i]*x[j] for j in range(3)) >= 250
sum(c[i]*x[j] for j in range(3)) >= 15
sum(d[i]*x[j] for j in range(3)) >= 90
solve()
You can see where I've changed the second [i] to a [j] and added a for j in range (3). That means a list will be created inside that sum call.
You can run that and see how close it is to what you're trying to do, as I'm not completely sure myself.