Sieve of Erasthostenes

sieve.py

def create_list(n):
  l = []
  for x in range(2,n+1):
    l.append(x)
  return l 
 
def get_remove_factors(start, n, inc):
  s = set()
  for i in range(start, n+1, inc):
    if i > start:
      s.add(i)
  return s
 
def get_next_prime(l, last_prime, non_primes):
  if last_prime < 2:
    return 2
  for i in [x for x in l if x > last_prime]:
    if i not in non_primes:
      return i
 
  return None
 
n = 25
next_prime = 2
non_primes = set()
 
while next_prime:
  non_primes = non_primes.union(get_remove_factors(next_prime, n, next_prime))
  next_prime = get_next_prime([x for x in range(2,n+1)], next_prime, non_primes)
 
print(non_primes)
print(set([x for x in range(2, n+1)]).difference(non_primes))