Re: [m-users.] lists and sets, unordered or ordered.

Volker Wysk <[email protected]> Tue, 03 Oct 2023 23:13:40 +0200
Newsgroups	gmane.comp.lang.mercury.general
Message-ID	<[email protected]>
Am Dienstag, dem 03.10.2023 um 22:07 +0100 schrieb Sean Charles
(emacstheviking):
> In my detection, the same missile might hit more than one object if they
> are close: thus I only wanted to process it once even of it hits five
> things, so I wanted deduped list just to save setting the hit flag five
> times if that makes sense.
> 
> I checked out all the others sets, the only one I saw that looked good was
> set_unordlist but is says 'may contain duplicates'.
> 
> How do I get an unsorted deduped list from a set then, educate me, i sure
> as hell need it!

With the the set_c234.to_sorted_list/1 function, for instance. I still don't
know why your set needs to be unsorted.

V.

> 
> HAHA It's possible I have missed it in the melee, like 'cirle' not 'circle' las week, it's late, I'm tired
> :D
> 
> > On 3 Oct 2023, at 22:04, Volker Wysk <[email protected]> wrote:
> > 
> > Hi
> > 
> > You can get a sorted de-duped list from a set. Why do you need an unsorted
> > one? If it's efficiency, you need to have it sorted, unless you have only a
> > few elements.
> > 
> > But be aware that there is the "set" module and five "set_*" modules. The
> > "set" is using ordered lists. That's inefficient for large sets. Use the
> > other modules when you have a big set.
> > 
> > Cheers,
> > Volker
> > 
> > Am Dienstag, dem 03.10.2023 um 21:55 +0100 schrieb Sean Charles
> > (emacstheviking):
> > > Indeed. nothing in my drafts folder and I swear it was complete before I hit send... well,
> > > basically,
> > > is there a reason you can't get an unsorted de-duped list from a set?
> > > 
> > > That's all...   :D
> > > 
> > > > On 3 Oct 2023, at 21:53, Volker Wysk <[email protected]> wrote:
> > > > 
> > > > Hi, Sean
> > > > 
> > > > Your message suddenly stops in the middle of a sentence.
> > > > 
> > > > Volker
> > > > 
> > > > Am Dienstag, dem 03.10.2023 um 21:39 +0100 schrieb Sean Charles
> > > > (emacstheviking):
> > > > > I've just completed a generic typeclass based collision detection system and learned quite a bit doing it!
> > > > > 
> > > > > As I was reading the module docs, it seems that there is no 'unordered set without duplicates' unless I missed it, which is entirely reasonable.
> > > > > 
> > > > > The output from the collision detection  is two sets of integers, these are the identifiers of the missiles and the things that were hit at the moment. I now want to take this list and then set the '^hit' flag for every missile in that list, for example, the existing code will then no longer render it and remove it on the next iteration.
> > > > > 
> > > > > I used sets because they de-dupe as you go, meaning that my checking process is simply iterating two loops, m x n, m missiles and n moving targets, for now it is naive and will probably always be fine given the limited numbers of things on screen at any one time.
> > > > > 
> > > > > There seems to be no way to get an unordered, deduplicated list from a set, I can use set_unordlist but that leaves duplicates.
> > > > > 
> > > > > 
> > > > > For now I've decided to use set_unordlist, at the cost of maybe updating the same missile record more than once poost-collision detection, it's not going to kill anything really but mentally, and from a purity point of view it feels 'less optimal' than I wanted. Failing that I might just usr  list.member and use lists for everything like I did!
> > > > > 
> > > > > I just wondered what the reasons were for not having the ability to get an unsorted 
> > > > > _______________________________________________
> > > > > users mailing list
> > > > > [email protected]
> > > > > https://lists.mercurylang.org/listinfo/users
> > > > 
> > > > _______________________________________________
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> > > > [email protected]
> > > > https://lists.mercurylang.org/listinfo/users
> > > 
> > 
> > _______________________________________________
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>

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