Question

I have two modules: “factors.py” and “primes.py”. In “factors.pyc”, I have a function that should find all the prime factors of a number. In it, I import 2 functions from “primes.py”. I have a dictionary in “primes.py”, which is declared as global (prior to it being defined). When I try to use it in the code of “factors.py”, I get this error:

Traceback (most recent call last):
  File "<pyshell#2>", line 1, in <module>
    pFactors(250)
  File "D:\my_stuff\Google Drive\Modules\factors.py", line 53, in pFactors
    for i in primes_dict:
NameError: global name 'primes_dict' is not defined

Here are my codes:

In “factors.py”:

def pFactors(n):
   import primes as p
   from math import sqrt
   from time import time
   pFact, primes, start, limit, check, num = [], [], time(), int(round(sqrt(n))), 2, n
   if p.isPrime(n):
      pFact = [1, n]
   else:
      p.prevPrimes(limit)
      for i in primes_dict:
         if primes_dict[i]:
            primes.append(i)
   #other code

And in “primes.py”:

def prevPrimes(n):
    if type(n) != int and type(n) != long:
        raise TypeError("Argument <n> accepts only <type 'int'> or <type 'long'>")
    if n < 2:
        raise ValueError("Argument <n> accepts only integers greater than 1")
    from time import time
    global primes_dict
    start, primes_dict, num = time(), {}, 0
    for i in range(2, n + 1):
        primes_dict[i] = True
    for i in primes_dict:
        if primes_dict[i]:
            num = 2
            while (num * i < n):
                primes_dict[num*i] = False
                num += 1
    end = time()
    print round((end - start), 4), ' seconds'
    return primes_dict #I added this in based off of an answer on another question, but it still was unable to solve my issue

prevPrimes(n) works in the manner it was intended to. However, because I am unable to access primes_dict, pFactors(n) doesn’t work.

How can I use the dictionary primes_dict (created in one module) in another module? Thanks in advance.

Answer 1

Anything defined in primes will be under the name you import it as. Since you imported it as p, then primes_dict is accessible as p.primes_dict. You could, if you wanted, do

from primes import primes_dict

to have it as a top-level name.