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Groups > comp.lang.python > #39975

Re: groupby behaviour

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2013/2/26 Ian Kelly <ian.g.kelly@gmail.com>:
> On Tue, Feb 26, 2013 at 9:27 AM, andrea crotti
> <andrea.crotti.0@gmail.com> wrote:
>> So I was trying to use groupby (which I used in the past), but I
>> noticed a very strange thing if using list on
>> the result:
>
> As stated in the docs:
>
> """
> The returned group is itself an iterator that shares the underlying
> iterable with groupby(). Because the source is shared, when the
> groupby() object is advanced, the previous group is no longer visible.
> So, if that data is needed later, it should be stored as a list:
> """
> --
> http://mail.python.org/mailman/listinfo/python-list


I should have read more carefully sorry, I was in the funny situation
where it would have actually worked in the production code but it was
failing in the unit tests (because I was using list only there).

It's very weird though this sharing and still doesn't really look
rightl, is it done just for performance reasons?

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Re: groupby behaviour andrea crotti <andrea.crotti.0@gmail.com> - 2013-02-26 17:09 +0000
  Re: groupby behaviour Paul Rubin <no.email@nospam.invalid> - 2013-02-26 09:35 -0800

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