> can duplicate on windows, both of these are fast: > ~. 1 ,.~ ?. 1000000 2$100
> ~. 1 ,.~ ?. 1000000 4$100 That is the same here. It gets slow when the fourth column in the second case is (almost) a constant A =: ?1000000 3$100 6!:2 'echo $~.A,.1234' 632325 4 25.7533 Ben On Fri, 25 Nov 2022 at 01:12, 'Pascal Jasmin' via Programming < programm...@jsoftware.com> wrote: > can duplicate on windows, both of these are fast: > > ~. 1 ,.~ ?. 1000000 2$100 > > ~. 1 ,.~ ?. 1000000 4$100 > > > > > > On Thursday, November 24, 2022 at 12:40:33 a.m. EST, Elijah Stone < > elro...@elronnd.net> wrote: > > > > > > That looks rather serious. It seems some problem with the hashing > function is > causing an unreasonably high rate of collisions. As a temporary > workaround, > you can try using ~.&.:(1&|."1), or use the 32-bit version. > > On Thu, 24 Nov 2022, Ben Gorte wrote: > > > G'day, > > > > > > Still J-ing along, I believe I ran into a little performance issue. > > > > I can strip it down into: > > > > > > A3=:?1000000 3$100 NB. three columns of random numbers 0 .. 99 > > > > A31 =: A3,.1 NB. with an extra column of 1-s > > > > A4=:?1000000 4$100 NB. or four random columns > > > > 6!:2 'echo $~.A3' > > > > 632783 3 > > > > 0.037673 > > > > 6!:2 'echo $~.A31' > > > > 632783 4 > > > > 24.6091 > > > > That's 600 times longer! > > > > > > However, > > > > 6!:2 'echo $~.A4' > > > > 995025 4 > > > > 0.43277 > > > > is again much quicker. > > > > > > This is consistent over versions 807, 903 and 904, all with Ubuntu linux. > > > > > > I do need the fourth column and it has many 1-s (not all). > > > > > > Thanks, > > > > Ben > > ---------------------------------------------------------------------- > > 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
