flatten a list of list

Chris Rebert clp2 at rebertia.com
Sun Aug 16 12:59:52 CEST 2009


On Sun, Aug 16, 2009 at 6:49 AM, Steven
D'Aprano<steve at remove-this-cybersource.com.au> wrote:
> On Sun, 16 Aug 2009 05:55:48 -0400, Chris Rebert wrote:
>> On Sun, Aug 16, 2009 at 5:47 AM, Terry<terry.yinzhe at gmail.com> wrote:
>>> Hi,
>>>
>>> Is there a simple way (the pythonic way) to flatten a list of list?
>>> rather than my current solution:
>>>
>>> new_list=[]
>>> for l in list_of_list:
>>>    new_list.extend(l)
>>>
>>> or,
>>>
>>> new_list=reduce(lambda x,y:x.extend(y), list_of_list)
>>
>> #only marginally better:
>> from operator import add
>> new_list = reduce(add, list_of_list)
>
> Surely that's going to be O(N**2)?

The OP asked for "simple", not "best", "most proper", or "fastest". My
comment was intended to mean that the code was marginally *simpler*,
not faster.

Cheers,
Chris
-- 
http://blog.rebertia.com



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