[racket-dev] union-find

I understood you to be asking for something like this:

  (check-equal? (uf-same-set? (uf-new 1) (uf-new 2)) #f)
  (check-equal? (uf-same-set? (uf-new 1) (uf-new 1)) #f)
  (check-equal? (let ([a (uf-new 1)]
                      [b (uf-new 1)])
                  (uf-union! a b)
                  (uf-same-set? a b))
                #t)

No?


On Tue, Jan 29, 2013 at 6:51 PM, Sam Tobin-Hochstadt <samth at ccs.neu.edu>wrote:

> But wouldn't that equate two un-unioned invocations of (uf-new 1)?
>
> On Tue, Jan 29, 2013 at 7:47 PM, Robby Findler
> <robby at eecs.northwestern.edu> wrote:
> > But I should probably provide that, since it can be done more reliably
> > inside the library.
> >
> > Robby
> >
> >
> > On Tue, Jan 29, 2013 at 6:46 PM, Robby Findler <
> robby at eecs.northwestern.edu>
> > wrote:
> >>
> >>
> >>
> >>
> >> On Tue, Jan 29, 2013 at 4:20 PM, Sam Tobin-Hochstadt <samth at ccs.neu.edu
> >
> >> wrote:
> >>>
> >>> This is probably a silly question, but don't you also need some way to
> >>> check if two sets have been unioned?  Does your application not need
> >>> that?
> >>>
> >>
> >> You check to see if their canonical element is the same.
> >>
> >> Robby
> >>
> >>>
> >>> Sam
> >>>
> >>> On Tue, Jan 29, 2013 at 4:51 PM, Robby Findler
> >>> <robby at eecs.northwestern.edu> wrote:
> >>> > I've just pushed an implementation of the union-find algorithm to the
> >>> > data/
> >>> > collection. I didn't do it quite the way wikipedia recommends, but
> >>> > instead
> >>> > made the sets be little containers whose canonical element can be
> >>> > mutated.
> >>> >
> >>> > This suits my purposes well, but I wanted to ask if someone on the
> list
> >>> > knows why the wikipedia way is better.
> >>> >
> >>> > Also, I wasn't sure about the names, so I put "uf-" on the front of
> >>> > everything to discourage people from using this when they really want
> >>> > racket/set. Maybe there is a better way, tho?
> >>> >
> >>> > Robby
> >>> >
> >>> >
> >>> > _________________________
> >>> >   Racket Developers list:
> >>> >   http://lists.racket-lang.org/dev
> >>> >
> >>
> >>
> >
>
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