Convert Instagram long id into shortcode and vice versa.

shortcoder.py

# -*- coding: utf-8 -*-
# ported from: https://gist.github.com/sclark39/9daf13eea9c0b381667b61e3d2e7bc11


class Shortcoder(object):

    LOWER = 'abcdefghijklmnopqrstuvwxyz'
    UPPER = LOWER.upper()
    NUMBERS = '0123456789'

    def __init__(self):
        self.ALPHABET = self.UPPER + self.LOWER + self.NUMBERS + '-_'
        self.reverse = {self.ALPHABET[i]: i for i in range(len(self.ALPHABET))}
        self.radix = len(self.ALPHABET)

    def lid2code(self, lid):
        lid = int(lid)
        code = []
        while True:
            remainder = lid % self.radix
            lid = lid // self.radix
            code.append(self.ALPHABET[remainder])
            if not lid:
                break
        return ''.join(code[::-1])

    def code2lid(self, code):
        code = str(code)
        lid = 0
        exponent = 1
        code = code[::-1]
        for c in code:
            lid = lid + exponent * self.reverse[c]
            exponent = exponent * self.radix
        return lid


if __name__ == '__main__':
    shortcoder = Shortcoder()
    lid = 908540701891980503
    code = 'ybyPRoQWzX'
    assert lid == shortcoder.code2lid(code)
    assert code == shortcoder.lid2code(lid)