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
