How about this?
fdeb2=: 13 :'y#~-.('' ''=y)*.1|.'' ''=y'
fdeb2
] #~ [: -. (' ' = ]) *. 1 |. ' ' = ]
Linda
-----Original Message-----
From: programming-boun...@jsoftware.com
[mailto:programming-boun...@jsoftware.com] On Behalf Of Marshall Lochbaum
Sent: Wednesday, January 04, 2012 12:42 PM
To: Programming forum
Subject: Re: [Jprogramming] Faster deb
If you really want top-of-the-line performance, you'll have to go to a
sequential machine. Here's my solution, which leaves the leading and
trailing blanks in, then specifically deletes them.
I don't claim that these tests are universal; it's quite plausible that a
different mixture of blanks and words would give different results.
Of course, benefits are marginal, and if performance is REALLY critical, I
would advise just wasting the 20 lines and 10 minutes that it takes to code
the thing in C.
ws =. ' ',TAB,LF
dlb =. }.^:(ws e.~{.) NB. delete leading blank
dtb =. }:^:(ws e.~{:) NB. delete trailing blank
m =. ws -.@:e.~ a.
s =. 2 2 2$ 0 1 1 2 0 2 1 0
sdeb =: [: dlb@:dtb (1;s;m)&;:
fdeb =: [: dlb [ #~ [: -. [: (] *. 1&|.) ' ' = [
test =. ; ' test'&,&.> (1e5?@$10) <@$"0 ]' '
100 (6!:2) 'deb test'
0.0167294
100 (6!:2) 'sdeb test'
0.012571
100 (6!:2) 'fdeb test'
0.0162943
(deb -: sdeb) test
1
(deb -: fdeb) test
1
Marshall
On Wed, Jan 4, 2012 at 11:53 AM, Ian Clark <earthspo...@gmail.com> wrote:
> okay, I didn't read Raul's posting properly.
>
> On Wed, Jan 4, 2012 at 4:44 PM, Ian Clark <earthspo...@gmail.com> wrote:
> > Raul's points are valid, but as a technique I like it. I'm going to
> > add it to my collection of idioms for a monograph on string-handling.
> >
> > Rotate-and-compare can be generalized to detect any given letter
> > followed/preceded by some other. But in the speed stakes, there's
> > often extra housekeeping handling the string ends.
> >
> > Harking back to a recent thread where (;:inv) came up, how about these
> too?
> >
> > wdeb=: ;:inv @ ;:
> > udeb=: ] &. ;: NB. a faster variant of the same idea
> >
> > Not as fast as either deb or fdeb, (besides mishandling punctuation)
> > but with a certain idiot appeal. And try replacing (]) with (|.),
> > (~.), sort, etc.
> >
> > In my monograph, (;:) will have a chapter to itself.
> >
> >
> > On Wed, Jan 4, 2012 at 1:54 PM, Raul Miller <rauldmil...@gmail.com>
> wrote:
> >> As you point out, these are not equivalent.
> >>
> >> # TEST=: ' this is a test '
> >> 26
> >> # deb TEST
> >> 14
> >> # fdeb TEST
> >> 15
> >>
> >> Note also:
> >> # ]&.;: TEST
> >> 14
> >>
> >> That said:
> >> # ]&.;: ' Don''t do this... '
> >> |open quote
> >>
> >> Also, the timing difference between 3.446e_6 and 3.293e_6 is
> inconsequential.
> >>
> >> --
> >> Raul
> >>
> >> On Wed, Jan 4, 2012 at 2:14 AM, Alan Stebbens <a...@stebbens.org> wrote:
> >>> "delete extra blanks" from strings.ijs has this definition:
> >>>
> >>> deb =: #~ (+. (1: |. (> </\)))@(' '&~:)
> >>>
> >>> NB. Here is a slightly faster deb:
> >>>
> >>> fdeb =: [ #~ [: -. [: (] *. 1&|.) ' ' = [
> >>>
> >>> NB. s is the test string; w is its boxed words
> >>>
> >>> w=.;:s=.'now is the time for all good men to come to the aid of
> their country'
> >>> w
> >>> +---+--+---+----+---+---+----+---+--+----+--+---+---+--+-----+-------+
> >>> |now|is|the|time|for|all|good|men|to|come|to|the|aid|of|their|country|
> >>> +---+--+---+----+---+---+----+---+--+----+--+---+---+--+-----+-------+
> >>>
> >>> NB. show
> >>> 1000 tx 'deb ,>w'
> >>> 3.446e_6 3072
> >>>
> >>> 1000 tx 'fdeb ,>w'
> >>> 3.293e_6 3072
> >>>
> >>> NB. same value for both the old and new fun
> >>> (deb -: fdeb),>w
> >>> 1
> >>>
> >>> NB. the results match the original string
> >>> s -: fdeb ,>w
> >>> 1
> >>>
> >>> However, it's not exactly the same as deb: it doesn't remove a single
> leading blank, as does deb (which, IMHO, is not necessarily an "extra"
> blank anyway).
> >>>
> >>> Alan
> >>>
> >>>
> >>>
> >>> ----------------------------------------------------------------------
> >>> For information about J forums see http://www.jsoftware.com/forums.htm
> >> ----------------------------------------------------------------------
> >> 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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