But if you use dyadic /: you won't get g , will you? I'm looking forward to reading all the quotes again.
Linda -----Original Message----- From: programming-boun...@forums.jsoftware.com [mailto:programming-boun...@forums.jsoftware.com] On Behalf Of Roger Hui Sent: Wednesday, March 05, 2014 11:00 PM To: Programming forum Subject: Re: [Jprogramming] a good bar bet! I respectfully suggest you study the dyad /: . The fact that the dyad /: is defined to do what it does is one of Ken Iverson's masterstrokes<http://keiapl.org/anec/#sort> . On Wed, Mar 5, 2014 at 7:46 PM, Linda Alvord <lindaalv...@verizon.net>wrote: > For me slow J is fast enough, but I really was delighted when this worked > at all. No doubt it is slow. > > > ]A=:?10$100 > 63 92 51 92 39 15 43 89 36 69 > f=:/: > g=:/: { ] > h=:f;g > h A > --------------------T-----------------------------┐ > │5 8 4 6 2 0 9 7 1 3│15 36 39 43 51 63 69 89 92 92│ > L-------------------+------------------------------ > > Linda > > > > -----Original Message----- > From: programming-boun...@forums.jsoftware.com > [mailto:programming-boun...@forums.jsoftware.com] On Behalf Of Roger Hui > Sent: Wednesday, March 05, 2014 8:45 PM > To: Programming forum > Subject: Re: [Jprogramming] a good bar bet! > > It's necessary to have the g because I asked for both the sort (s) and the > grade, which would be the g. > > The problem arose in an application where the sort and the grade are used > for something else. > > > > On Wed, Mar 5, 2014 at 4:32 PM, Don Kelly <d...@shaw.ca> wrote: > > > Why is it necessary to have 'g' > > > > repeating the process on my machine which is obviously slower gives an > > insignifcant time difference. > > > > 20 timer 's=:/:~x [ /:x' > > > > 0.172937 > > > > > > 20 timer 's=:/:~x [ g=:/:x' > > > > 0.173672 > > > > Is it because storage is necessary and it is just as fast to store to a > > named location rather than to some temporary storage? > > Space differences seem small. > > > > Don Kelly > > > > > > On 05/03/2014 12:11 PM, Joe Bogner wrote: > > > >> Yes, the grade is done regardless. Here's my reasoning: In the > >> incumbent version, s is taken from the grade with from { which is > >> slower than just resorting. > >> It seems like the difference between sorting and selecting by indexes. > >> I am surprised if that's the answer though because selecting by index > >> should be fast since it's a contiguous array. > >> > >> jtifrom looks more complicated than jtsortc but I haven't been able to > >> figure out how jtsortc works. > >> > >> On Wed, Mar 5, 2014 at 2:50 PM, Roger Hui <rogerhui.can...@gmail.com> > >> wrote: > >> > >>> x=: a.{~ 1e7 ?@$ 256 > >>> timer=: 6!:2 > >>> > >>> 10 timer 's=:x{~g=:/:x' > >>> 0.136961 > >>> 10 timer 's=:/:~x [ g=:/:x' > >>> 0.0765459 > >>> > >>> 10 timer '/:~x' > >>> 0.012887 > >>> 10 timer 'x{~g' > >>> 0.065751 > >>> 10 timer '/:x' > >>> 0.0606987 > >>> > >>> > >>> > >>> On Wed, Mar 5, 2014 at 11:45 AM, Roger Hui <rogerhui.can...@gmail.com> > >>> wrote: > >>> > >>> That's my alternative faster expression as well. But the more > >>>> interesting > >>>> question is, why is it faster? Since we do the grade in both cases, > the > >>>> comparison is between /:~x and g{x (or x{~g) with g pre-computed. The > >>>> answer does not depend knowledge specific to J. > >>>> > >>>> > >>>> > >>>> > >>>> > >>>> On Wed, Mar 5, 2014 at 11:38 AM, Joe Bogner <joebog...@gmail.com> > >>>> wrote: > >>>> > >>>> Sorting and grading separately seems faster > >>>>> > >>>>> timer=: 6!:2 > >>>>> x=:(1e7 $ 26?26) { 'abcdefghijklmnopqrstuvwxyz' > >>>>> NB. incumbent > >>>>> timer 's=: x{~g=: /:x' > >>>>> 0.0914002 > >>>>> > >>>>> NB. alternate > >>>>> timer 'S=: /:~x[G=: /:x' > >>>>> 0.0668677 > >>>>> > >>>>> s-:S > >>>>> 1 > >>>>> G-:g > >>>>> 1 > >>>>> > >>>>> > >>>>> I am speculating that sorting does it in place? which is faster than > >>>>> the selection from the grade > >>>>> > >>>>> > >>>>> > >>>>> On Wed, Mar 5, 2014 at 2:02 PM, Raul Miller <rauldmil...@gmail.com> > >>>>> wrote: > >>>>> > >>>>>> Hmm... > >>>>>> > >>>>>> G=:a.i.S=:/:~x > >>>>>> is faster. > >>>>>> > >>>>>> But while s-:S, g and G are different. > >>>>>> > >>>>>> So I'm drawing a blank here, on how to make the grade. > >>>>>> > >>>>>> Thanks, > >>>>>> > >>>>>> -- > >>>>>> Raul > >>>>>> > >>>>>> > >>>>>> > >>>>>> On Wed, Mar 5, 2014 at 1:52 PM, Roger Hui < > rogerhui.can...@gmail.com> > >>>>>> > >>>>> wrote: > >>>>> > >>>>>> Suppose x is a long vector of characters and you need both its sort > >>>>>>> > >>>>>> and its > >>>>> > >>>>>> grade. Can you do it faster than s=: x{~g=: /:x ? > >>>>>>> > >>>>>>> Posed this way, the answer is of course yes. But how, and why is > it > >>>>>>> faster? > >>>>>>> ------------------------------------------------------------ > >>>>>>> ---------- > >>>>>>> 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 > >>>>> > >>>>> > >>>> > ---------------------------------------------------------------------- > >>> 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 > > > ---------------------------------------------------------------------- > 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 ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
