bases.py

#!python

import string


def decode(str_num, base):
    """
    Decode given number from given base to base 10.
    str_num -- string representation of number in given base
    base -- base of given number
    """
    assert 2 <= base <= 36
    # TODO: Decode number
    result = 0
    for digit in range(1, len(str_num) + 1):
        value = str_num[-digit]
        if ord(value) >= 97 and ord(value) <= 172:
            value = int(ord(value) - 87)
        elif ord(value) >= 65 and ord(value) <= 90:
            value = int(ord(value) - 55)
        else:
            value = int(value)
        placeholder = digit - 1
        result += value * base ** placeholder
    return result

def encode(num, base):
    """
    Encode given number from base 10 to given base.
    num -- the number in base 10
    base -- base to convert to
    """
    assert 2 <= base <= 36
    # TODO: Encode number
    num_rep={10:'a',
         11:'b',
         12:'c',
         13:'d',
         14:'e',
         15:'f',
         16:'g',
         17:'h',
         18:'i',
         19:'j',
         20:'k',
         21:'l',
         22:'m',
         23:'n',
         24:'o',
         25:'p',
         26:'q',
         27:'r',
         28:'s',
         29:'t',
         30:'u',
         31:'v',
         32:'w',
         33:'x',
         34:'y',
         35:'z'}
    result = ''
    current = num
    while current != 0:
        remainder = current % base
        if 36 > remainder > 9:
            remainder_string = num_rep[remainder]
        elif remainder >= 36:
            remainder_string = '(' + str(remainder) + ')'
        else:
            remainder_string = str(remainder)
        result += remainder_string
        current = current / base
    return result

def convert(str_num, base1, base2):
    """
    Convert given number from base1 to base2.
    """
    assert 2 <= base1 <= 36
    assert 2 <= base2 <= 36
    # TODO: Convert number
    in_base_ten = decode(str_num, base1)
    return encode(in_base_ten, base2)


def main():
    import sys
    args = sys.argv[1:]  # Ignore script file name
    if len(args) == 3:
        str_num = args[0]
        base1 = int(args[1])
        base2 = int(args[2])
        result = convert(str_num, base1, base2)
        print('{} in base {} is {} in base {}'.format(str_num, base1, result, base2))
    else:
        print('Usage: {} number base1 base2'.format(sys.argv[0]))


if __name__ == '__main__':
    main()