Prime factorization - list

Question

I am trying to implement a function primeFac() that takes as input a positive integer n and returns a list containing all the numbers in the prime

Answer 1

I've tweaked @user448810's answer to use iterators from itertools (and python3.4, but it should be back-portable). The solution is about 15% faster.

import itertools

def factors(n):
    f = 2
    increments = itertools.chain([1,2,2], itertools.cycle([4,2,4,2,4,6,2,6]))
    for incr in increments:
        if f*f > n:
            break
        while n % f == 0:
            yield f
            n //= f
        f += incr
    if n > 1:
        yield n

Note that this returns an iterable, not a list. Wrap it in list() if that's what you want.