It is, nevertheless, an implementation. And anyone that feels like doing so can supply other alternates (or replace it, if they feel theirs is good enough).
Thanks, -- Raul On Mon, Sep 8, 2014 at 5:28 PM, Devon McCormick <[email protected]> wrote: > This looks like a transliteration from another language - not J-like at > all. Once clue is that it's several times as long as many of the other > implementations. > > > On Mon, Sep 8, 2014 at 4:05 PM, Joe Bogner <[email protected]> wrote: > >> I found an implementation of red-black trees on rosettacode: >> http://rosettacode.org/wiki/Pattern_matching#J ... It might be relevant >> or >> may not be. >> >> On Mon, Sep 8, 2014 at 3:45 PM, Devon McCormick <[email protected]> >> wrote: >> >> > A little research clarified what we see here: apparently it's part of the >> > definition of a binary tree that the left node be smaller than its parent >> > but the right one is greater. Right away, I see a problem for the >> > predecessor-index representation of a tree that I'm advocating as it does >> > not distinguish between right and left nodes as it is usually >> implemented. >> > >> > >> > On Mon, Sep 8, 2014 at 3:03 PM, Devon McCormick <[email protected]> >> > wrote: >> > >> > > Do you have a reference to a good example of this? Looking at the >> > > "before" and "after" pictures on the right here - >> > > http://en.wikipedia.org/wiki/Self-balancing_binary_search_tree - the >> > > rebalancing seems arbitrary as it preserves some relations but changes >> > > others. >> > > >> > > >> > > On Mon, Sep 8, 2014 at 2:30 PM, Dan Bron <[email protected]> wrote: >> > > >> > >> Raul wrote: >> > >> > Note that J already supports trees. >> > >> >> > >> Devon wrote: >> > >> > I have J code that uses trees which I run daily and >> > >> > have been doing so for years. >> > >> >> > >> Pascal wrote: >> > >> > I think trees are done at least ok, if not "right" already. >> > >> >> > >> Challenge: express, in J, the logic of rebalancing a heap (say, a >> > >> Fibonacci >> > >> heap, but I'm not particularly picky). >> > >> >> > >> For the sake of this exercise, you may ignore considerations of >> > efficiency >> > >> (though that's a bit of a self-contradiction, because heaps are >> > frequently >> > >> introduced specifically for the sake of efficiency). I am only >> > interested >> > >> in the directness, simplicity, elegance (lyricality) of the notation, >> in >> > >> its current form, for expressing ideas about trees. We can make it >> > >> efficient "later" (Pepe's TCO utility is a start). >> > >> >> > >> -Dan >> > >> >> > >> >> > >> >> > >> ---------------------------------------------------------------------- >> > >> For information about J forums see >> http://www.jsoftware.com/forums.htm >> > >> >> > > >> > > >> > > >> > > -- >> > > Devon McCormick, CFA >> > > >> > > >> > >> > >> > -- >> > Devon McCormick, CFA >> > ---------------------------------------------------------------------- >> > For information about J forums see http://www.jsoftware.com/forums.htm >> > >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm >> > > > > -- > Devon McCormick, CFA > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
