[New-bugs-announce] [issue17862] itertools.chunks(iterable, size, fill=None)

anatoly techtonik report at bugs.python.org
Sun Apr 28 18:13:10 CEST 2013


New submission from anatoly techtonik:

The history:
2007 - http://bugs.python.org/issue1502
2009 - http://bugs.python.org/issue6021

I'd like to resurrect this proposal again, but name it:
  itertools.chunks(iterable, size, fill=None)

Two reasons.
1. practicality  - top itertools request on StackOverflow
http://stackoverflow.com/search?tab=votes&q=%5bpython%5d%20%2bitertools

2. performance
the time should be a constant for a fixed-length iterable regardless of a size of chunk, but in fact the time is proportional to the size of chunk

{{{
import timeit

print timeit.timeit(
  'grouper(30000, "x"*400000)', setup='from __main__ import grouper', number=1000
)
print timeit.timeit(
  'grouper(300000, "x"*400000)', setup='from __main__ import grouper', number=1000
)
}}}

1.52581005407
14.6219704599


Addressing odd length user stories from msg87745:
1. no exceptions - odd end is an easy check if you need it
2. fill-in value - provided
3. truncation - just don't set fill-in value
3.1. if you really need fill-in as None, then an itertools.TRUNCATE value can be used as a truncation parameter
4. partially filled-in tuple - not sure what that means

Raymond, your opinion is critical here. =)

----------
components: Library (Lib)
messages: 187995
nosy: rhettinger, techtonik
priority: normal
severity: normal
status: open
title: itertools.chunks(iterable, size, fill=None)
versions: Python 3.3, Python 3.4, Python 3.5

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue17862>
_______________________________________


More information about the New-bugs-announce mailing list