使用Python查找所有不同的组合

Question

I want to create a function in python that as input takes a list with an unspecified amount of strings whose length is also not standard or the same with each other. The input would be like this:

list = ['1234', '4', '97', ... , '542']

The first element of this list represents all the possible numbers that could be the first digit of a number, the second element the possible numbers that could be the second digit and so on. As output, I want to have a list with all the possible numbers that could be generated this way. Here is an example:

input = ['12', '45', '865']
output = ['148', '146', '145', '158', '156', '155',
 '248', '246', '245', '258', '256', '255']

Is there an algorithm for this? I am not completely new to python but this problem has me at a loss. Thanks for any help.

Answer 1

from itertools import product

input = ['12', '45', '865']

[''.join(prod) for prod in product(*input)]

# ['148', '146', '145', '158', '156', '155', '248', '246',
#  '245', '258', '256', '255']

itertools.product takes a number of iterables as parameters, and yields their cartesian product.
As your iterables (your strings) are in a list, we use the *input syntax to unpack the elements of the list to separate positional parameters.

Answer 2

Tested with Python 2.7

Input = ['12', '45', '865']
out = [[]]

# algo
for liste in Input:
    out = [x + [y] for x in out for y in liste]
    #print out # un comment to see how algo works

index = 0
while index < len(out):
    out[index] = ''.join(out[index])
    index += 1

print out

# prodcues:
# ['148', '146', '145', '158', '156', '155',
#  '248', '246', '245', '258', '256', '255']
# The while loop can be reduced to:
# print [''.join(liste) for liste in out]