Try this where f and A2 are as in your post: out <-f(A2[A2>0]) replace(matrix(0, length(A2), ncol(out)), A2 > 0, out)
On 7/27/06, Robin Hankin <[EMAIL PROTECTED]> wrote: > Hi > > > I have a little vector function that takes a vector A of strictly > positive integers > and outputs a matrix M each of whose columns is the vector, modified in > a complicated combinatorical way. > > Now I want to generalize the function so that A can include zeroes. > Given A, > I want to strip out the zeroes, pass it to my function, and pad M > with rows at positions corresponding to the zeroes of A. > > Commented, minimal, self-contained, reproducible toy example follows. > > > f <- function(a){cbind(a,a+1,rev(a))} #real function a ghastly > nightmare > > A <- 1:5 > f(A) > a > [1,] 1 2 5 > [2,] 2 3 4 > [3,] 3 4 3 > [4,] 4 5 2 > [5,] 5 6 1 > > > # f() works as desired. > > # Now introduce A2, that includes zeroes. In my application, f(A2) > would fail > because of the zeroes. > > A2 <- c(1,0,0,2,4,0,3) > > I can strip the zeroes out and call f(): > f(A2[A2>0]) > a > [1,] 1 2 3 > [2,] 2 3 4 > [3,] 4 5 2 > [4,] 3 4 1 > > which is fine. How to put the zeroes back in in the appropriate rows > and get the following: > > > cbind(c(1,0,0,2,4,0,3),c(2,0,0,3,5,0,4),c(3,0,0,4,2,0,1)) > [,1] [,2] [,3] > [1,] 1 2 3 > [2,] 0 0 0 > [3,] 0 0 0 > [4,] 2 3 4 > [5,] 4 5 2 > [6,] 0 0 0 > [7,] 3 4 1 > > > > > > anyone? > > > > -- > Robin Hankin > Uncertainty Analyst > National Oceanography Centre, Southampton > European Way, Southampton SO14 3ZH, UK > tel 023-8059-7743 > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.