[Python-Dev] [Python-ideas] itertools.chunks(iterable, size, fill=None) (original) (raw)

anatoly techtonik techtonik at gmail.com
Wed Jul 4 11:57:20 CEST 2012

On Fri, Jun 29, 2012 at 11:32 PM, Georg Brandl <g.brandl at gmx.net> wrote:

On 26.06.2012 10:03, anatoly techtonik wrote:

Now that Python 3 is all about iterators (which is a user killer feature for Python according to StackOverflow - http://stackoverflow.com/questions/tagged/python) would it be nice to introduce more first class functions to work with them? One function to be exact to split string into chunks. itertools.chunks(iterable, size, fill=None) Which is the 33th most voted Python question on SO - http://stackoverflow.com/questions/312443/how-do-you-split-a-list-into-evenly-sized-chunks-in-python/312464 P.S. CC'ing to python-dev@ to notify about the thread in python-ideas. Anatoly, so far there were no negative votes -- would you care to go another step and propose a patch?

Was about to say "no problem", but in fact - there is. Sorry from whining from my side and thanks for nudging. The only thought that a simple task of copy/pasting relevant code from http://docs.python.org/library/itertools.html?highlight=itertools#recipes will require a few hours waiting of download (still not everybody has a high-speed internet) makes me switch to other less time consuming tasks before getting around to it. These tasks become more important in a few hours, and basically I've passed through this many times before. It then becomes quite hard to switch back.

I absolutely don't mind someone else being credited for the idea, because ideas usually worthless without implementation. It will be interesting to design how the process could work in a separate thread. For now the best thing I can do (I don't risk even to mention anything with 3.3) is to copy/paste code from the docs here:

from itertools import izip_longest def chunks(iterable, size, fill=None): """Split an iterable into blocks of fixed-length""" # chunks('ABCDEFG', 3, 'x') --> ABC DEF Gxx args = [iter(iterable)] * size return izip_longest(fillvalue=fill, *args)

BTW, this doesn't work as expected (at least for strings). Expected is: chunks('ABCDEFG', 3, 'x') --> 'ABC' 'DEF' 'Gxx' got: chunks('ABCDEFG', 3, 'x') --> ('A' 'B' 'C') ('D' 'E' 'F') ('G' 'x' 'x')

Needs more round tuits definitely.

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