Permutation generator - first attempt

permutation_generator.py

"""
Given an integer 'n', create a generator  that will return a new permutation
of the integers between 1 and n, until all the permutations have been
exhausted.

Ex: input: 3
    output: 123, 132, 321, 231, 312, 213
"""


def generate_permutations_for_number_of_digits(n):
    if n <= 1:
        return 1

    digit_list = [x for x in range(1, n+1)]

    return generate_permutations_for(digit_list=digit_list)


def generate_permutations_for(digit_list):
    num_of_digits = len(digit_list)

    if num_of_digits == 2:
        base = int(str(digit_list[0]) + str(digit_list[1]))
        yield base
        swapped_base = int(str(digit_list[1]) + str(digit_list[0]))
        yield swapped_base
    else:
        for x in range(1, num_of_digits + 1):
            fixed_digit = digit_list[x-1]
            temp_list = digit_list[:]
            del temp_list[x-1]

            for y in generate_permutations_for(digit_list=temp_list):
                num_so_far = int(str(fixed_digit) + str(y))
                yield num_so_far

print(list(generate_permutations_for_number_of_digits(5)))
print(len(list(generate_permutations_for_number_of_digits(5))))