Importing a matrix from Python to Pyomo - numpy

Question

I have a matrix defined in Python: (name of the document matrix.py)
N = 4
l = N
k = N
D = np.zeros((l,k))
for i in range(0,l):
for j in range(0,k):
if (i==j):
D[i,j] = 2
else:
D[i,j] = 0
D[0,0] = (2*N**2+1)/6
D[-1,-1] = -(2*N**2+1)/6
print(D)
I want to use it in Pyomo, and i did:
import matrix
.
.
.
m.f_x1 = Var(m.N)
def f_x1_definition(model,i):
for j in m.N:
return m.f_x1[j] ==sum(D[i,j]*m.x1[j] for j in range(value(m.n)))
m.f_x1_const = Constraint(m.N, rule = f_x1_definition)
But I get the next error:
NameError: global name 'D' is not defined
How can I do it?

Answer 1

When you import a module in python using the syntax
import foo
all the things defined in the foo module will be available within the foo namespace. That is, if foo.py contains:
import numpy as np
a = 5
D = np.zeros((1,5))
when you import the module with import foo, then you can access a, and D with:
import foo
print(foo.a)
print(foo.D)
If you want to pull the symbols from foo directly into your local namespace, you would instead use the from ... import ... syntax:
from foo import a,D
print(a)
print(D)