If you look at the J7.01beta dictionary, Appendix B, dictionary/special.htm, and release/cateachslash.htm you'll see that ,.&.>/ has been improved, and:
t2=: 3 : '6!:2 '',.&.>/t'' [ t=. <"1 (y,43)$''abc'''"0 t2 1e5*2^i.4 0.040837 0.0361222 0.0804401 0.139528 I have not tried it but ,.&:>/ is probably quadratic. ----- Original Message ----- From: Henry Rich <[email protected]> Date: Thursday, June 17, 2010 8:56 Subject: Re: [Jprogramming] Combine named lists as matrix To: Programming forum <[email protected]> > Oh, I didn't see the fine print under ,/ . > > Ric was planning to use ,.&:>/ which isn't listed as > improved, and > seems to be quadratic. > > So I'll just say 'avoid quadratic performance for large operands'. > > Henry Rich > > Roger Hui wrote: > >> ,./ will work but it will have quadratic performance. > >> Avoid for large operands. > > > > t0=: 3 : '6!:2 '',./t'' [ t=. > (y,43)$''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
