Permutation of all characters in strings

Question

I am trying to generate a sequence using characters in a different string.

Example:

Input: ["abcdef", "xyz", "-/", "98765"]
Output: ax-9,ax-8,ax-7,ax-6,ax-5,ax/9,ax/8,ax/7,ax/6,ax/5,ay-9,ay-8,ay-7,ay-6,ay-5

Code:

def print_taxi_serial_numbers(params, code, level, offsets, n):
    params_length = len(params)
    print("TT11 :: ", code, level, offsets)
    if level == params_length-1:
        for c in params[level]:
            print("{}{}".format(code,c))
    else:
        while True:
            print("LEVEL :: ", level)
            if level == 0:
                code = ""
            code = "{}{}".format(code, params[level][offsets[level]])
            offsets[level] += 1
            level = level + 1
            if level >= params_length:
                print("LEVEL1 :: ", level, " params_length :: ", params_length, " yy :: ", offsets, " zz ", params)
                return
            print_taxi_serial_numbers(params, code, level, offsets, n)
            print("TT :: ", code, level, offsets)

#Function Call
params = ["abcdef", "xyz", "-/", "98765"]
print_taxi_serial_numbers(params, "", 0, len(params)*[0], 10)

I am making some mistake in resetting the params.

Asked By: MANISH ZOPE

||

Source

Answer 1

You don’t really need recursion and carry around a bunch of arguments. Just use the cartesian product (for which there are utils):

from itertools import product

def print_taxi_serial_numbers(params):
    for p in product(*params):
        print(''.join(p))

>>> print_taxi_serial_numbers(["abcdef", "xyz", "-/", "98765"])
ax-9
ax-8
ax-7
ax-6
ax-5
# ...

If you are hell-bent on doing it yourself, you can still keep it simple:

def taxi_serial_numbers(params):
    if not params:
        return [""]
    result = []
    first, *params = params
    for char in first:
        for tsn in taxi_serial_numbers(params):
            result.append(char + tsn)
    return result

>>> taxi_serial_numbers(["abcdef", "xyz", "-/", "98765"])
['ax-9', 'ax-8', 'ax-7', 'ax-6', 'ax-5', 'ax/9', 'ax/8', ... ]

Note that the recursion is much easier when your function returns something meaningful instead of just having side-effects (like console prints). You can still use the function return value to get your print display:

for tsn in print_taxi_serial_numbers(params):
    print(tsn)

Answered By: user2390182

Permutation of all characters in strings

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