baseN encode

basen.py

import string


def baseEncode(number, base=0):
    if isinstance(number, str):
        number = long(number)
    if not isinstance(number, (int, long)):
        raise TypeError('number must be an integer')
    if number < 0:
        raise ValueError('number must be positive')
    if base < 0:
        raise ValueError('base must be positive')

    alphabet = string.digits + string.ascii_letters + '_'

    if base == 0:
        base = len(alphabet)

    baseN = ''
    while number:
        number, i = divmod(number, base)
        baseN = alphabet[i] + baseN

    return baseN or alphabet[0]


if __name__ == '__main__':
    print baseEncode(12311231231234345365464)  # 39pBAwzAwRVux
    print baseEncode(101)   # 1C
    print baseEncode('12311231231234345365464')  # 39pBAwzAwRVux