code.py

from string import ascii_letters, digits

ALPHABET = digits + ascii_letters

__author__ = 'phil'


def convert_to_code(number, minimal_length=1, alphabet=ALPHABET):
    """Converts a decimal id number into a shortened code."""
    base = len(alphabet)  # base to convert to
    chars = []
    while number:
        chars.append(alphabet[number % base])
        number //= base
    chars.reverse()  # moved right to left, so reverse order
    res = ''.join(chars)  # convert stored characters to single string
    return ''.join(('0' * (minimal_length - len(res)), res))


def resolve_to_id(code, alphabet=ALPHABET):
    """Converts the shortened code back to an id number in decimal form."""
    base = len(alphabet)
    size = len(code)
    number = 0
    for i in range(0, size):  # convert from higher base back to decimal
        number += alphabet.index(code[i]) * (base ** (size - i - 1))
    return number


print convert_to_code(140906)  #  AEG
print resolve_to_id('AEG')  #  140906