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