base-change.py

class BaseChanger:    
    BASE = 10
    NEW_BASE = None
    MINUS_SIGN = False
    
    def __init__(self, n, new_base, n_base=BASE):
        
        self.NEW_BASE = new_base
        if n_base:
            self.BASE = n_base
        
        if new_base < 2 or new_base > 36:
            raise NotImplementError('New base number must between 2 and 36')      

        self.n = int(str(n), base=n_base)
        
        if self.n < 0:
            self.MINUS_SIGN = True
            self.n = self.n * -1
    
        self.digitalize()
                
    def digitalize(self):
        self.digits = []
        
        if self.n == 0 or self.n < self.NEW_BASE:
            self.digits = [0]    
        else:
            n = self.n
            b = self.NEW_BASE
            while n >= b:
                # mod = n % b
                # div = n // b
                div, mod = divmod(n, b)
                self.digits.insert(0, mod)
                n = div
            self.digits.insert(0, n)
        
        return self.digits          

    @staticmethod
    def encode(digits):
        map_str = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ'
        return ''.join(map_str[c] for c in digits)
    
    @property
    def encoding(self):
        s = self.encode(self.digits)
        if self.MINUS_SIGN:
            return '-' + s
        return s