On Fri, Dec 20, 2019 at 4:15 PM Wes Turner wrote:
>
> How slow and space-inefficient would it be to just implement the set methods
> on top of dict?
Speed: Dict doesn't cache the position of the first item. Calling
next(iter(D)) repeatedly is O(N) in worst case.
Space: It waste 8bytes per
How slow and space-inefficient would it be to just implement the set
methods on top of dict?
Do dicts lose insertion order when a key is deleted? AFAIU, OrderedDict do
not lose insertion order on delete. Would this limit the utility of an
ordered set as a queue? What set methods does a queue need
[Nick]
> I must admit that I was assuming without stating that a full OrderedSet
> implementation would support the MutableSequence interface.
Efficient access via index position too would be an enormous new
requirement, My bet: basic operations would need to change from O(1)
to O(log(N)).
On Fri., 20 Dec. 2019, 1:56 pm Tim Peters, wrote:
> So what problem(s) would a dynamic ordered set really be aiming at? I
> don't know. Consistency & predictability I understand and appreciate,
> but little beyond that. Even FIFO ordering is somewhat a PITA, since
> `next(iter(set))` is an
[David Mertz ]
> It's not obvious to me that insertion order is even the most obvious or
> most commonly relevant sort order. I'm sure it is for Larry's program, but
> often a work queue might want some other order. Very often queues
> might instead, for example, have a priority number assigned
[Nick]
> I took Larry's request a slightly different way:
Sorry, I was unclear: by "use case" I had in mind what appeared to me
to be the overwhelming thrust of the _entirety_ of this thread so far,
not Larry's original request.
> he has a use case where he wants order preservation (so built in
On Thu, Dec 19, 2019 at 5:39 PM Nick Coghlan wrote:
> I took Larry's request a slightly different way: he has a use case where
> he wants order preservation (so built in sets aren't good), but combined
> with low cost duplicate identification and elimination and removal of
> arbitrary elements
Hi,
Le mer. 18 déc. 2019 à 16:43, Julien Danjou a écrit :
> The only way to retrieve the current exception is via sys.excinfo or
> PyErr_GetExcInfo in C. However, the issue is that they don't take a
> PyThreadState as argument, but use _PyThreadState_GET() to retrieve the
> thread state.
If we
On Fri., 20 Dec. 2019, 2:58 am Tim Peters, wrote:
> [Nick Coghlan ]
> > Starting with "collections.OrderedSet" seems like a reasonable idea,
> > though - that way "like a built-in set, but insertion order preserving"
> will
> > have an obvious and readily available answer, and it should also
> >
OrderedSet implementations:
- https://github.com/methane/cpython/pull/23/files
- https://pypi.org/search/?q=orderedset
- https://pypi.org/project/orderedset/
- https://code.activestate.com/recipes/576694/
- https://pypi.org/project/ordered-set/
-
[Nick Coghlan ]
> Starting with "collections.OrderedSet" seems like a reasonable idea,
> though - that way "like a built-in set, but insertion order preserving" will
> have an obvious and readily available answer, and it should also
> make performance comparisons easier.
Ya, I suggested starting
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seasons_greetings()
On behalf of the entire Python development community, and the currently serving
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Python
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