Best pattern/idiom

[Michele Simionato]

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,)]

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