Converting the output of itertools.permutations from list of tuples to list of strings

Question

Having some issues with a list after using the itertools permutations function.

from itertools import permutations

def longestWord(letters):
    combinations = list(permutations(letters))
    for s in combinations:
        ''.join(s)
    print(combinations)

longestWord("aah")  

The output looks like this:

[('a', 'a', 'h'), ('a', 'h', 'a'), ('a', 'a', 'h'), ('a', 'h', 'a'), 
 ('h', 'a', 'a'), ('h', 'a', 'a')]

I would like this to be a simple list, but it seems to be coming out as a list of tuples(?). Can anyone help me format this so it comes out as the following:

['aah', 'aha', 'aah', 'aha', 'haa', 'haa']

Answer 1

from itertools import permutations

def longestWord(letters):
    return [''.join(i) for i in permutations(letters)]

print(longestWord("aah"))

Result:

['aah', 'aha', 'aah', 'aha', 'haa', 'haa']

A few suggestions:

1. Don't print inside the function, return instead and print the returned value.
2. Your naming of variable combination is not good, as combination is different from permutation
3. Your join wasn't doing anything, join doesn't change value inline, it returns the string
4. The function name does not represent what it does. longest word?

Answer 2

Permutations returns an iterator yielding tuples so you need to join them. A map is a nice way to do it instead of your for-loop.

from itertools import permutations

def longestWord(letters):
  combinations = list(map("".join, permutations(letters)))
  print(combinations)

longestWord("aah")  

The way you were doing it, you were joining the letters in each tuple into a single string but you weren't altering the combinations list.