On 9 January 2012 08:53, Phil Wiles <philip.wi...@gmail.com> wrote: > I have a multidimensional array - in this case with 4 dimensions of x,y,z > and time. I'd like to take the time derivative of this matrix, i.e. > perform the diff operator along dimension number 4.
"apply" can do that, but you may need to reorder the dimensions of the result. a <- array(1:81,dim=c(3,3,3,3)) b <- apply(a, 1:3, diff) b <- aperm(b,c(2:4,1)) dim(b) -- Vincent ______________________________________________ R-help@r-project.org 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.
