how to permute every combination of 4 chars, without duplicates?

Question

I want to make something that takes in the len(char) and permutes every single combination from all letters + numbers.

So far, I got my code to do it, but in my case out of the 1679616 possible combinations (36 ** 4), only about 1061340 of them are non duplicates, (running it once), and I can't figure out how to re-loop it until it gets a total of 1679616 combinations.

I've tried changing the ran of the loop every time it gets a duplicate, but that makes the loop take up to 20hours, so I prefer not doing that. I've tried countless other ways, but all failed. Instead of using random, I want to eventually loop through each element, and find each individual combination, but I have also failed at this.

import random

elements = [A-Z, 0-9]ect
code1 = ""
perms = []
actualperms = []


for e in range(6718464):
    code1 += random.choice(elements)
    if len(code1) == 4:
    code = "VLSC" + code1.upper() + "FE12"
    perms.append(code)
    code1 = ''

for elm in perms:
    if elm not in actualperms:
        actualperms.append(elm)

with open('code.json', 'w') as outfile:
    json.dump(acutalcombos, outfile)

The output shows only 1100000 permutations, but I want the total 36**4. It also takes a long time for it to export as JSON, so If there is a faster way please tell me.

Also, I know my code is extremely inefficient, I started a couple of months ago

what are the `elements` precisely? from `elements = [A-Z, 0-9]ect` it's hard to guess what you really mean... — hiro protagonist, Apr 17 '19 at 04:56
Its being answered before: https://stackoverflow.com/questions/1457814/get-every-combination-of-strings — FranktheTank, Apr 17 '19 at 04:57
elements = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9'] — ArunCanCode, Apr 17 '19 at 04:58

gmds · Answer 1 · 2019-04-17T05:07:04.097

1

Use itertools.product:

import json

from itertools import product
from string import ascii_lowercase, digits

result = list(product(ascii_lowercase + digits, repeat=4))

print(len(result) == 36 ** 4)

with open('permutations.txt', 'w') as f:
    json.dump(result, f)

Output:

True

edited Apr 17 '19 at 05:07

answered Apr 17 '19 at 04:58

gmds

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I meant like, when it adds code to a list, if code is already there, then don't add it. – ArunCanCode Apr 17 '19 at 05:04
@ArunCanCode Okay, I get what you mean now. Use `product` instead of `permutations` (see my edit). – gmds Apr 17 '19 at 05:07

how to permute every combination of 4 chars, without duplicates?

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