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References: <efcc61e6-f132-4f14-80b5-0536816b6c7b@googlegroups.com> <mailman.14101.1411042251.18130.python-list@python.org> <roy-E21095.08580518092014@news.panix.com> <mailman.14103.1411047208.18130.python-list@python.org> <roy-7E9ED1.19515818092014@news.panix.com>
Date: Fri, 19 Sep 2014 12:45:11 +1000
Subject: Re: Is there a canonical way to check whether an iterable is ordered?
From: Chris Angelico <rosuav@gmail.com>
Cc: "python-list@python.org" <python-list@python.org>
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Xref: csiph.com comp.lang.python:78054

On Fri, Sep 19, 2014 at 9:52 AM, Roy Smith <roy@panix.com> wrote:
> In article <mailman.14103.1411047208.18130.python-list@python.org>,
>  Chris Angelico <rosuav@gmail.com> wrote:
>
>> The one thing you can rely on (and therefore must comply with, when
>> you design an iterable) is that iteration will hit every element
>> exactly once.
>
> Does it actually say that somewhere?  For example:
>
> for i in bag.pick_randomly_with_replacement(n=5):
>    print i
>
> shouldn't do that.

When you pick randomly from a population, you create a new population,
which may have duplicates compared to the original. (For efficiency's
sake it probably won't all actually exist immediately, but
conceptually it does exist.) That's what you're iterating over - not
the bag itself.

ChrisA