py itertools?

[Chris Rebert]

> On Dec 19, 12:48 pm, Chris Rebert <c... at rebertia.com> wrote:
>> On Sat, Dec 19, 2009 at 2:54 AM, mattia <ger... at gmail.com> wrote:
>> > Hi all, I need to create the permutation of two strings but without
>> > repeat the values, e.g. 'ab' for me is equal to 'ba'. Here is my
>> > solution, but maybe the python library provides something better:
>>
>> >>>> def mcd(a, b):
>> > ...     if b == 0:
>> > ...         return a
>> > ...     else:
>> > ...         return mcd(b, a % b)
>> > ...
>> >>>> def mcm(a, b):
>> > ...     return int((a * b) / mcd(a, b))
>> > ...
>> >>>> s1 = 'abc'
>> >>>> s2 = 'wt'
>> >>>> m = mcm(len(s1), len(s2))
>> >>>> set(zip(s1*m, s2*m))
>> > {('a', 'w'), ('a', 't'), ('b', 'w'), ('c', 't'), ('b', 't'), ('c', 'w')}
>>
>> > Any help?
>>
>> Surprised you didn't think of the seemingly obvious approach:
>>
>> def permute_chars(one, two):
>>     for left in set(one):
>>         for right in set(two):
>>             yield (left, right)
>>
>> >>> list(permute_chars('abc', 'wt'))
>>
>> [('a', 'w'), ('a', 't'), ('b', 'w'), ('b', 't'), ('c', 'w'), ('c', 't')]

On Sun, Dec 20, 2009 at 3:21 AM, Parker <xenoszh at gmail.com> wrote:
>>>> a = 'qwerty'
>>>> b = '^%&$#'
>>>> c = [(x,y) for x in a for y in b]
>>>> c
> [('q', '^'), ('q', '%'), ('q', '&'), ('q', '$'), ('q', '#'), ('w',
> '^'), ('w', '%'), ('w', '&'), ('w', '$'), ('w', '#'), ('e', '^'),
> ('e', '%'), ('e', '&'), ('e', '$'), ('e', '#'), ('r', '^'), ('r',
> '%'), ('r', '&'), ('r', '$'), ('r', '#'), ('t', '^'), ('t', '%'),
> ('t', '&'), ('t', '$'), ('t', '#'), ('y', '^'), ('y', '%'), ('y',
> '&'), ('y', '$'), ('y', '#')]
>
>
> This one is better and simple.

But fails if either of the input strings has repeated characters.
(Although writing it as a comprehension is indeed much briefer.)

Whether this matters, who knows, since the OP's spec for the function
was rather vague...

Cheers,
Chris
--
http://blog.rebertia.com