Base62 encode/decode tools (convert number to string)

base62codec.py

#!/usr/bin/env python
#-*- coding:utf-8 -*-
# Base62 tools (convert number <=> string)
# v1.0/20161228
# python 2.x/3.x supported
#
# based on work by Ady Liu <imxylz@gmail.com>
#author: Ahmad gharbeia <ahmad@arabdigitalexpression.org>
#github: github.com/agharbeia

import sys

digits = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'
radix = len(digits)


def decode(s):
    n, exp = 0, 1
    for d in reversed(s):
        n += exp*digits.index(d)
        exp *= radix
    return n

def encode(n):
    if n < 0 : raise Exception("negatice number " + n + " entered")
    if n == 0 : return '0'
    s = ''
    while n != 0:
        s = (digits[n % radix]) + s
        n = int(n / radix)
    return s


if __name__ == '__main__':
    if len(sys.argv) < 2:
        print("Usage: base62.py <num>...")
        sys.exit(1)
    width = max(len(x) for x in sys.argv[1:])
    for argv in sys.argv[1:]:
        try:
            num = int(argv)
            print('%*s %s %s' % (width,argv,'ENCODE',encode(num)))
        except ValueError:
            print('%*s %s %s' % (width,argv,'DECODE',decode(argv)))

demo.sh

$ python base62.py 16075652386131968 1bCQSgeUyk
16075652386131968 ENCODE 1bCQSgeUyk
       1bCQSgeUyk DECODE 16075652386131968
$ python3 base62.py 16075652386131968 1bCQSgeUyk
16075652386131968 ENCODE 1bCQSgeUyk
       1bCQSgeUyk DECODE 16075652386131968