mk <mrk...@gmail.com> wrote:
>Brian Allen Vanderburg II wrote:
>> I think it may be just a 'little' more efficient to do this:
>>
>> def flatten(x, res=None):
>> if res is None:
>> res = []
>> for el in x:
>> if isinstance(el, (tuple, list)):
>> flatten(el, res)
>> else:
>> res.append(el)
>> return res
>
>
>Hmm why should it be more efficient [than
def flatten(x):
res = []
for el in x:
if isinstance(el,list):
res.extend(flatten(el))
else:
res.append(el)
return res
]? extend operation should not be very costly?
It's not a question of extend/append, it's the fact that your
original function creates (and destroys) a new list for every
recursive call. Which, if you've got large nested lists, will
have an impact.
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