"number-in-base" ``oneliner''

[Bengt Richter]

On Sat, 30 Oct 2004 07:48:34 GMT, bokr at oz.net (Bengt Richter) wrote:

>On Sat, 30 Oct 2004 06:07:23 GMT, bokr at oz.net (Bengt Richter) wrote:
>[...]
>>Maybe something useful in this? Not very tested (and not terribly clear either ;-)
>>
>> >>> def number_in_base(x, N, digits):
>> ...     return x==0 and digits[0] or '-'[:x<0] + ''.join([d for d in iter(
>> ...                 lambda qr=[abs(x),0]:qr[0] and (
>> ...                     qr.__setslice__(0,2,divmod(qr[0],N)) or digits[qr[1]])
>> ...                 , 0)][::-1])
>> ...
>
>Alternatively, a little more compactly (though I feel guilty about the -1 ;-):
>
> >>> def number_in_base(x, N=10, digits='0123456789ABCDEF'):
> ...     return '-'[:x<0] + ''.join(list(iter(lambda qr=[abs(x),-1]: (qr[0] or qr[1]<0) and (
> ...         qr.__setslice__(0,2,divmod(qr[0],N)) or digits[qr[1]]), False))[::-1])
> ...

Yet another, prefixing digits instead of joining reversed list:

 >>> def number_in_base(x, N=10, digits='0123456789ABCDEF'):
 ...     return '-'[:x<0]+reduce(lambda s,c:c+s, iter(lambda qr=[abs(x),-1]: (qr[0] or qr[1]<0)
 ...         and (qr.__setslice__(0,2,divmod(qr[0],N)) or digits[qr[1]]), False))
 ...
 >>> number_in_base( 0 , 2, '01')
 '0'
 >>> number_in_base( 1 , 2, '01')
 '1'
 >>> number_in_base(126, 2, '01')
 '1111110'
 >>> number_in_base(-126, 2, '01')
 '-1111110'

Regards,
Bengt Richter