Brad wrote:
> On Jul 2, 9:40 pm, "Pablo Torres N." <tn.pa...@gmail.com> wrote:
>> If it is speed that we are after, it's my understanding that map and
>> filter are faster than iterating with the for statement (and also
>> faster than list comprehensions). So here is a rewrite:
>>
>> def split(seq, func=bool):
>> t = filter(func, seq)
>> f = filter(lambda x: not func(x), seq)
>> return list(t), list(f)
>>
>
> In my simple tests, that takes 1.8x as long as the original solution.
> Better than the itertools solution, when "func" is short and fast. I
> think the solution here would worse if func was more complex.
>
> Either way, what I am still wondering is if people would find a built-
> in implementation useful?
>
> -Brad
A built-in/itertools should always try to provide the general solution
to be as useful as possible, something like this:
def group(seq, func=bool):
ret = {}
for item in seq:
fitem = func(item)
try:
ret[fitem].append(item)
except KeyError:
ret[fitem] = [item]
return ret
definitely won't be faster, but it is a much more general solution.
Basically, the function allows you to group sequences based on the
result of func(item). It is similar to itertools.groupby() except that
this also group non-contiguous items.
--
http://mail.python.org/mailman/listinfo/python-list
