ishexdigit()

[Raymond Hettinger]

[Tim Roberts]
> Well, more Pythonish yet is to avoid the extraneous local variables, 
> avoid the use of a type as a parameter name, and use as many 
> little-used builtins as possible:
>
>   def ishexdigit(char):
>       return char in string.hexdigits
>
>   def ishexstring(strng):
>       return filter(ishexdigit, strng) == strng

[Uwe Schmitt]
> better/faster/more pythonic:
> 
>          return reduce(lambda a,b: a and ishexdigit(b), strng, True)

In the vague category of Most Pythonic, code using "filter", "lambda",
and "and" tend to be losers.  Straight-forward loops run reasonably
fast and are much more clear:
 
   def ishexstring(s):
        for c in s:
            if c not in '0123456789abcdefABCDEF':
                return False
        return True


The category of Fastest Code is much less vague but tends towards
using fancy tricks:

    def ishexstring(s):
        try:
            int(s, 16)
        except ValueError:
            return False
        return True


The category of Cutest Code tends to make creative use of data
structures:

    def ishexstring(s):
        return not sets.Set(s).difference('0123456789abcdefABCDEF')



Raymond Hettinger