increasing string size through loop

Question

what's a simple way to increase the length of a string to an arbitrary integer x? like 'a' goes to 'z' and then goes to 'aa' to 'zz' to 'aaa', etc.

Answer 1

That should do the trick:

def iterate_strings(n):
    if n <= 0:
        yield ''
        return
    for c in string.ascii_lowercase:
        for s in iterate_strings(n - 1):
            yield c + s

It returns a generator. You can iterate it with a for loop:

for s in iterate_strings(5)

Or get a list of the strings:

list(iterate_strings(5))

If you want to iterate over shorter strings too, you can use this function:

def iterate_strings(n):
    yield ''
    if n <= 0:
        return
    for c in string.ascii_lowercase:
        for s in iterate_strings(n - 1):
            yield c + s

Answer 2

Here's my solution, similar to Adam's, except it's not recursive. :].

from itertools import product
from string import lowercase

def letter_generator(limit):
    for length in range(1, limit+1):
        for letters in product(lowercase, repeat=length):
            yield ''.join(letters)

And it returns a generator, so you can use a for loop to iterate over it:

for letters in letter_generator(5):
    # ...

Have fun!

(This is the second time today I found itertools.product() useful. Woot.)