Have you considered j numbers? data=:0j1 0j2 0j3 1j1 1j3 2j1 4j1 9 o. data 0 0 0 1 1 2 4 11 o. data 1 2 3 1 3 1 1
2011/5/5 John Randall <[email protected]> > I have a set of ordered pairs of nonnegative integers (representing > pixels that are set in a binary image). To speed up access, I want to > produce an array s of boxes such that (x,y) is an ordered pair if and > only if y e. x {:: s . Keys would work perfectly for this except for > skipped x-values, so I work around it, essentially inserting a bogus > y-value for every x-value, and then removing it. > > data=:>0 1;0 2;0 3;1 1;1 3;2 1;4 1 > > slice=:3 : 0 > 'X Y'=.|:/:~ y > m=.>:>./X > n=.>:>./Y > X=.(i.m),X > Y=.(m#n),Y > -.&n &.> X</.Y > ) > slice data > +-----+---+-++-+ > |1 2 3|1 3|1||1| > +-----+---+-++-+ > > I also have a test verb. > > test=:3 : 0 > y=./:~y > s=.slice y > y-:;(<"0 i.#s)(,"_ 0)&.> s > ) > > test data > 1 > > Does anyone have any suggestions as to how to do this better? > > Best wishes, > > John > > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > -- Björn Helgason, Verkfræðingur Fornustekkum II 781 Hornafirði, t-póst: [email protected] gsm: +3546985532 twitter: @flugfiskur http://groups.google.com/group/J-Programming Tæknikunnátta höndlar hið flókna, sköpunargáfa er meistari einfaldleikans góður kennari getur stigið á tær án þess að glansinn fari af skónum /|_ .-----------------------------------. ,' .\ / | Með léttri lund verður | ,--' _,' | Dagurinn í dag | / / | Enn betri en gærdagurinn | ( -. | `-----------------------------------' | ) | (\_ _/) (`-. '--.) (='.'=) ♖♘♗♕♔♙ `. )----' (")_(") ☃☠ ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
