Henry,
I tried this in J5.04 (changed x y into x. y.) but it returned a syntax
error (e.g. 'aap' LevDist5 'taap')
³syntax error: LevDist5
³ z=.<./\&.(-&iz)( >:<.(j~:b)+|.!.j_index)z
What's wrong?
J6 works fine.
Jan.
On Sun, Dec 20, 2009 at 5:37 PM, Henry Rich <henryhr...@nc.rr.com> wrote:
> Well, let me give you my final version then:
>
> levdist=: 4 : 0"1
> 'a b'=. (/: #&>)x;y
> z=. >: iz =. i.#b
> for_j. a do.
> z=. <./\&.(-&iz) (>: <. (j ~: b) + |.!.j_index) z
> end.
> {:z
> )
>
> No way is this ever going to be a J primitive. And J does not allow
> overloading primitive names with user code. You'll have to give it a
> name and use it.
>
> I've not heard of Tanimoto distance, but we can work on that next.
>
> Henry Rich
>
> Jan Jacobs wrote:
> > Henry,
> > very good. For longer strings it is more than double so fast as the
> previous
> > version. In my test cases it even consumes less memory.
> > Is it possible to include this as a native function in J (e.g.
> overloading
> > -. or s:)?
> > Same question but now for Tanimoto distance?
> > Jan.
> >
> >
> > On 12/19/09, R.E. Boss <r.e.b...@planet.nl> wrote:
> >> Smart analysis. Chapeau!
> >>
> >>
> >> R.E. Boss
> >>
> >>
> >> -----Oorspronkelijk bericht-----
> >> Van: programming-boun...@jsoftware.com
> >> [mailto:programming-boun...@jsoftware.com] Namens Henry Rich
> >> Verzonden: zaterdag 19 december 2009 3:00
> >> Aan: Programming forum
> >> Onderwerp: [Jprogramming] Levenshtein distance
> >>
> >> I was working with R. E.'s compact implementation of the Levenshtein
> >> distance and I found an interesting equivalence:
> >>
> >> (<. >:)/\.&.|.
> >>
> >> can be replaced by
> >>
> >> (<./\@:- + ]) i...@#
> >>
> >> which uses a little more space but is quite a bit faster for large
> >> operands. So now I have the version:
> >>
> >> NB. Levenshtein distance between two strings
> >> levdist=: 4 : 0
> >> 'a b'=. (/: #&>)x;y
> >> z=. i.>:#b
> >> for_j. a do.
> >> z=. ((<./\@:- + ]) i...@#) ((j ~: b) + }:z) ({...@] , (<. }.)) >:z
> >> end.
> >> {:z
> >> )
> >>
> >>
> >> Henry Rich
> >> ----------------------------------------------------------------------
> >> For information about J forums see http://www.jsoftware.com/forums.htm
> >>
> >> ----------------------------------------------------------------------
> >> For information about J forums see http://www.jsoftware.com/forums.htm
> >>
> >
> >
> >
> ----------------------------------------------------------------------
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>
--
Jan Jacobs
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