Simple way to calculate prime factors

primez.py

#!/usr/bin/python3
#
# Copyright (c) 2014, Alexandre Hamelin <alexandre.hamelin gmail.com>
#
# Small program that calculates primes and print them on screen.


import sys


def primes():
    import itertools

    primes_list = [2, 3, 5]
    deltas = itertools.cycle([2, 2, 4, 2])
    diffs = [0, 1, 2]
    maxdiff = 0

    for i, p in enumerate(primes_list):
        yield p, diffs[i]

    n = p
    while True:
        try:
            n += deltas.__next__()
            N = n ** .5     # sqrt()
            is_prime = all([n % p != 0 for p in primes_list if p < N])
            if is_prime:
                primes_list.append(n)
                diffs.append(n - primes_list[-2])
                if diffs[-1] > maxdiff:
                    maxdiff = diffs[-1]
                    print('found new maxdiff {0} at {1}'.format(str(maxdiff), n))
                #yield n, diffs[-1]
        except KeyboardInterrupt:
            import time
            try:
                print('\nat prime {0}'.format(n))
                time.sleep(1)
            except KeyboardInterrupt:
                break


for p, diff in primes():
    #print(str(p) + ' ', end='')
    print(str(diff) + ' ', end='')    # show differences instead
    sys.stdout.flush()