how to use output of one file as input to another file in python - import

Question

like I have a code
def poly (x,a):
j=0
ans=[0]*len(x)
while (j<len(x)):
i=0
while(i<len(a)):
ans[j] = ans[j] + a[i]*((x[j])**i)
i=i+1
else:
j=j+1
else:
print ans
a=[1,1,1]
x=[1,1,1]
print poly(x,a)
now I want x in this file from another file containg program like:
def mult(x,q):
i=0
while(i<len(x)):
x[i] = x[i]*q
i=i+1
else:
print x
x=[1,1,1]
q=2
print mult(x,q)

Answer 1

Maybe this is a possible solution.
First: In your function definitions where you have "print ans" and "print x", I think you want return statements. i.e. "return ans" and "return x".
e.g.
def poly (x,a):
j=0
ans=[0]*len(x)
while (j<len(x)):
i=0
while(i<len(a)):
ans[j] = ans[j] + a[i]*((x[j])**i)
i=i+1
else:
j=j+1
else:
return ans # changed print to return
Then, assuming you have two separate program files (let's call them poly.py and mult.py) in which the given functions are separately defined you could write a new program file (e.g. polymult.py) which looks something like this:
#start code
# import programs poly.py and mult.py
# this will execute commands in these files
# but gives access to functions defined within
from poly import *
from mult import *
# Main
# define/reset the variables we need/want to use
a=[1,1,1]
x=[1,1,1]
q=2
# pass mult which returns new x into poly
print poly(mult(x,q),a)
#end code
A caveat to the way I wrote the above is that the files poly.py and mult.py have to be in the same directory/folder as the program importing them. (A simple alternative would be to simply define the functions (paste them in) in place of the import statements)
Also, if you just want to use them as imported functions as in my example you could remove all the code other than the actual function def's. Otherwise, when you execute polymult.py you will see the extra screen prints executed during the import of poly.py and mult.py