> ,./ will work but it will have quadratic performance. > Avoid for large operands.
t0=: 3 : '6!:2 '',./t'' [ t=. (y,43)$''abc'''"0 t1=: 3 : '6!:2 '',./t'' [ t=. (43,y)$''abc'''"0 t0 1e5*2^i.4 0.0979133 0.10202 0.194575 0.391258 t1 1e5*2^i.4 0.0770126 0.0742525 0.118406 0.235672 Looks linear to me. ----- Original Message ----- From: Henry Rich <[email protected]> Date: Thursday, June 17, 2010 4:55 Subject: Re: [Jprogramming] Combine named lists as matrix To: Programming forum <[email protected]> > I share your antipathy to ". but I think it is unfounded. > Surely it's > no different from using 3 : . > > ,./ will work but it will have quadratic performance. > Avoid for large > operands. > > Henry Rich > > > > Sherlock, Ric wrote: > > Thanks Henry > > This is much simpler but I have this (probably irrational) > negative feeling about using Do (".). I imagine that Evoke (~) > is probably just Do (".) under the covers so perhaps I just need > to get over it!! Reassurances welcome :-) > > > > The other thing I like about the other solution is that it > will give a length error if the columns are not equal length. > Whether that is desirable is obviously problem dependent, but in > my case it is a plus. Combining bits I get: > > > > ,.&:>/@:(".&.>)@;: 'Var1 Var2 Var3 Var4 Var5' > > > >> From: Henry Rich > >> Sent: Thursday, 17 June 2010 12:23 > >> > >> |:@:(".@>) ;: 'Var3 Var5 Var4 > Var1 Var2' > >> > >> Sherlock, Ric wrote: > >>> How best to form a matrix from a list of noun names where > each noun > >> is a list of values that will form a column in the matrix? > >>> Below is one solution, are there better ones? > >>> > >>> Named nouns: > >>> 'Var3 Var5 Var4 Var1 Var2' =: 5 7 ?...@$ 60 > >>> > >>> evoke=: 3 : 'y~' > >>> toMatrix =: [: ,.&:>/ [: evoke&.> ;: > >>> > >>> toMatrix 'Var1 Var2 Var3 Var4 Var5' > >>> 16 36 6 31 37 > >>> 0 46 35 32 40 > >>> 24 5 59 58 14 > >>> 24 17 52 0 6 > >>> 11 8 14 10 38 > >>> 13 48 39 42 13 > >>> 23 42 20 11 58 ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
