how is validator created in python and what are most popular libraries / modules to learn first

Question

I have a df which has a serial number generated with each new record. The serial number combines with some other part like state code, year of registration and category code. So it has a format like below:

| DOR    | Applicant's code |
|:-------|:--------------:|
|1-2-2018| MH2018-PAR-0689|
|1-2-2018| MH2018-PAR-0689|
|2-2-2018| MH2018-PAR-0690|
|2-2-2018| MH2018-OMC-0691|
|1-2-2018| UP2018-OMC-2461|
|1-2-2018| UP2018-FPR-2462|
|3-2-2018| UP2018-PAR-2463|
|1-2-2018| UP2018-OMC-2462|

Let's say 20 such records are generated in each state every month and there are 37 different state codes and 8 different category codes. I want to create a list of all possible Applicant's codes for next month which should be 37 x 1 x 8 x 20 possible values. I need guidance on how to code it with python and also if my approach is correct.

Answer 1

Use itertools doc for this purpose. Without knowing your exact codes I just made some lists up:

import itertools as it

nums = [x for x in range(37)]
single = ["_"]
abc = list('abcdefgh')
codes = [f"123{x}" for x in range(20)]


len(abc) * len(nums) * len(codes) # 5920

list(it.product(abc, single, nums, codes)) # len(...) -> 5920

This gives you:

[...]
 ('a', '_', 0, '1232'),
 ('a', '_', 0, '1233'),
 ('a', '_', 0, '1234'),
 ('a', '_', 0, '1235'),
 ('a', '_', 0, '1236'),
[...]
 ('b', '_', 12, '12315'),
 ('b', '_', 12, '12316'),
 ('b', '_', 12, '12317'),
 ('b', '_', 12, '12318'),
 ('b', '_', 12, '12319'),
[...]