[issue5350] Modification to pairwise in itertools recipes

2009-02-23 Thread Matteo Dell'Amico 

New submission from Matteo Dell'Amico de...@linux.it:

I feel that the pairwise recipe could be slightly more elegant if for
elem in b: break became a simpler next(b) (or b.next() for Python 2.x).
It is also more natural to modify the recipes to suit one's needs (e.g.,
returning items with a given gap between them, or convert the recipe to
k-wise iteration).

--
assignee: georg.brandl
components: Documentation
messages: 82626
nosy: della, georg.brandl
severity: normal
status: open
title: Modification to pairwise in itertools recipes

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[issue5350] Modification to pairwise in itertools recipes

2009-02-23 Thread Georg Brandl 

Georg Brandl ge...@python.org added the comment:

Assigning to Raymond.

Note that for elem in b: break and next(b) are not equivalent when b
is empty/exhausted.

--
assignee: georg.brandl - rhettinger
nosy: +rhettinger

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[issue5350] Modification to pairwise in itertools recipes

2009-02-23 Thread Matteo Dell'Amico 

Matteo Dell'Amico de...@linux.it added the comment:

Georg, you're right, there's a StopIteration to catch. My thinko was
mistaking the function for a generator where the exception propagation
would have done the right thing. The amended version now becomes

next(b)
for x, y in zip(a, b): yield x, y

...which is not that attractive anymore, also because it's slower. Sorry
for the error.

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[issue5350] Modification to pairwise in itertools recipes

2009-02-23 Thread David W. Lambert 

Changes by David W. Lambert lamber...@corning.com:


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nosy: +LambertDW

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[issue5350] Modification to pairwise in itertools recipes

2009-02-23 Thread Raymond Hettinger 

Raymond Hettinger rhettin...@users.sourceforge.net added the comment:

Applied in r69908 .

--
resolution:  - accepted
status: open - closed

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[issue5350] Modification to pairwise in itertools recipes

2009-02-23 Thread David W. Lambert 

David W. Lambert lamber...@corning.com added the comment:

Nice.  I had thought of this a while ago but found counter example,
probably using the empty iterator

def f():
raise StopIteration
yield


I didn't realize next had optional argument.

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[issue5350] Modification to pairwise in itertools recipes

2009-02-23 Thread Georg Brandl 

Georg Brandl ge...@python.org added the comment:

Shame on me, I forgot about the optional argument too.

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[issue5350] Modification to pairwise in itertools recipes

2009-02-23 Thread Matteo Dell'Amico 

Matteo Dell'Amico de...@linux.it added the comment:

great Raymond! :)

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