Python - Display Every Permutation of a List or Set of Strings

Question

As an example, I have the following list:

['ABC','DEF','GHI','JKL']

By my reckoning, there should be 26 combinations i.e.

ABCDEFGHIJKL
ABCDEFJKLGHI
ABCGHIDEFJKL
ABCGHIJKLDEF
ABCJKLDEFGHI
ABCJKLGHIDEF
...

How would I do this in Python?

Thanks

26? How'd you get that number? – user2357112 Apr 27 '16 at 21:51 — user2357112, Apr 27 '16 at 21:51
There's actually 4! = 4*3*2 = 24 permutations... – Moritz Apr 27 '16 at 21:52 — Moritz, Apr 27 '16 at 21:52
My maths is poor after 11pm :-( – pee2pee Apr 27 '16 at 21:52 — pee2pee, Apr 27 '16 at 21:52

score 3 · Answer 1 · answered Apr 27 '16 at 21:51

You're describing the basic use of itertools.permutations:

>>> import itertools
>>> L = ['ABC','DEF','GHI','JKL']
>>> for permutation in itertools.permutations(L):
...     print ''.join(permutation)
...     
ABCDEFGHIJKL
ABCDEFJKLGHI
ABCGHIDEFJKL
ABCGHIJKLDEF
...
JKLGHIDEFABC

score 0 · Answer 2 · answered Apr 27 '16 at 21:56

One approach that uses itertools:

>>> import itertools
>>> print list(itertools.permutations(['ABC','DEF','GHI','JKL'], 4))
[('ABC', 'DEF', 'GHI', 'JKL'), ('ABC', 'DEF', 'JKL', 'GHI'), ('ABC', 'GHI', 'DEF', 'JKL'), ('ABC', 'GHI', 'JKL', 'DEF'), ('ABC', 'JKL', 'DEF', 'GHI'), ('ABC', 'JKL', 'GHI', 'DEF'), ('DEF', 'ABC', 'GHI', 'JKL'), ('DEF', 'ABC', 'JKL', 'GHI'), ('DEF', 'GHI', 'ABC', 'JKL'), ('DEF', 'GHI', 'JKL', 'ABC'), ('DEF', 'JKL', 'ABC', 'GHI'), ('DEF', 'JKL', 'GHI', 'ABC'), ('GHI', 'ABC', 'DEF', 'JKL'), ('GHI', 'ABC', 'JKL', 'DEF'), ('GHI', 'DEF', 'ABC', 'JKL'), ('GHI', 'DEF', 'JKL', 'ABC'), ('GHI', 'JKL', 'ABC', 'DEF'), ('GHI', 'JKL', 'DEF', 'ABC'), ('JKL', 'ABC', 'DEF', 'GHI'), ('JKL', 'ABC', 'GHI', 'DEF'), ('JKL', 'DEF', 'ABC', 'GHI'), ('JKL', 'DEF', 'GHI', 'ABC'), ('JKL', 'GHI', 'ABC', 'DEF'), ('JKL', 'GHI', 'DEF', 'ABC')]
>>> print len(list(itertools.permutations(['ABC','DEF','GHI','JKL'], 4)))
24

Python - Display Every Permutation of a List or Set of Strings

2 Answers2