Is there a good python library that can turn numbe

Question

0 = 0
1 = 1
...
9 = 9
10 = a
11 = b
...
35 = z
36 = A
37 = B
...
60 = Z
61 = 10
62 = 11
... 
70 = 19
71 = 1a
72 = 1b

I don't know what this is called. Base something?

All I want is a function that can convert the numbers into these, and these back to numbers.

Is there an easy function that can do this?

Answer 1

>>> int("a", 36)
10
>>> int("z", 36)
35
>>> int("10", 36)
36

The other direction is more complicated, but try this ActiveState recipe.

Normally base conversions make no distinction between cases. I'm not sure how to completely extend this to make that distinction, but the recipe should give you a start.

Answer 2

You may inherit numbers.Number:

def baseN(base,alphabet='0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'):
    class _baseN(numbers.Number):
        digits=alphabet[:base]
        def __init__(self,value):
            if isinstance(value,int):
                self.value=value
                if self.value==0:
                    self.string='0'
                else:
                    tmp=[abs(value)]
                    while tmp[0]!=0:
                        tmp[:1]=divmod(tmp[0],base)
                    tmp=[alphabet[i] for i in tmp]
                    tmp[0]='-' if self.value<0 else ''
                    self.string=''.join(tmp)
            elif isinstance(value,str):
                assert(value.isalnum())
                self.string=str(value)
                self.value=0
                for d in value:
                    self.value=self.value*base+self.digits.index(d)
            else:
                self.value=0
                self.string='0'
        def __int__(self):
            return self.value
        def __str__(self):
            return self.string
        def __repr__(self):
            return self.string
        def __add__(self,another):
            return self.__class__(self.value+int(another))
    return None if base>len(alphabet) else _baseN

Found another bug. Change it to a factory function. Now may handle general situation.