Best pattern/idiom

[Chris Connett]

Michele Simionato wrote:
> Chris Connett <chrisccc_3k at yahoo.com> wrote in message news:<4117c3d8$1 at buckaroo.cs.rit.edu>...
> 
>>I was wondering if there were a well known pattern/idiom for breaking a 
>>sequence into a list of lists, each n elements long, e.g.
>>
>>[0,1,2,3,4,5,6,7,8,9,10,11] -> [[0,1,2,3],[4,5,6,7],[8,9,10,11]]
>>
>>This comes up reasonably often in my work, and every time I re-think 
>>about it, and come up with
>>[ lis[n:n+4] for n in range( 0, len( lis ), 4 ) ]
>>which seems very kludgy to me, since it uses a range and len, 2 mentions 
>>of the list identifier and 2 literal 4's (which is the size I want to 
>>break into this time).
>>
>>Is there a better way?
> 
> 
> From a post of mine of some time ago ...
> 
> 
>>>>import itertools
>>>>def chop(it, n):
> 
> ...     tup = (iter(it),)*n
> ...     return itertools.izip(*tup)
> ...
> 
>>>>list(chop([1,2,3,4,5,6],3)) [(1, 2, 3), (4, 5, 6)]
>>>>list(chop([1,2,3,4,5,6],2)) [(1, 2), (3, 4), (5, 6)]
>>>>list(chop([1,2,3,4,5,6],1))
> 
> [(1,), (2,), (3,), (4,), (5,), (6,)]
> 
>   Michele Simionato

That's slick! :)  Though, objectively, it might be less maintainable, 
since if I didn't know what it was doing, it'd take me a minute to 
figure it out.  I'll definitely keep that idea in my toolbox though!