Create all possible char combinations from an unknown amount of lists in python

Question

I want to create all possible character combinations from lists. The first char needs to be from the first array, the second char from the second array, etc.

If I have the following lists:

char1 = ['a','b','c']
char2 = ['1','2']

The possible strings, would be: a1, a2, b1, b2, c1 and c2. How do I make the code with makes all the combinations from an unknown amount of lists with an unknown size?

The problem is that I do not know, how many lists there will be. The amount of lists will be decided by the user, while the code is running.

This one is for an unknown amount of lists, therefore the two list multiplication code isn't useful here. — user31751, Nov 29 '17 at 18:27
"The amount of lists will be decided by the user, while the code is running." Then they will certainly not be in separate variables, but in a list of lists instead... **right**? — Karl Knechtel, Mar 02 '23 at 03:07

score 0 · Answer 1 · answered Nov 28 '17 at 19:59

0

That's a task for itertools.product()! Check out the docs: https://docs.python.org/2/library/itertools.html#itertools.product

>>> ["%s%s" % (c1,c2) for (c1,c2) in itertools.product(char1, char2)]
['a1', 'a2', 'b1', 'b2', 'c1', 'c2']

And yeah, it extends to a variable number of lists of unknown size.

answered Nov 28 '17 at 19:59

Pavel

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But how can it be modified so it works for an unknown amount of lists? – user31751 Nov 28 '17 at 20:05
https://stackoverflow.com/questions/10148834/python-itertools-product-with-variable-number-of-arguements – Pavel Nov 28 '17 at 20:09

score 0 · Accepted Answer · answered Nov 28 '17 at 20:24

As mentioned above, you can use itertools.product()

And since you don't know number of lists you can pass list of lists as an argument:

import itertools

lists = [
    ['a','b','c'],
    ['1','2']
]

["".join(x) for x in itertools.product(*lists)]

Result:

['a1', 'a2', 'b1', 'b2', 'c1', 'c2']

Create all possible char combinations from an unknown amount of lists in python

2 Answers2