Hesen Peng wrote:
Hi,
Thank you so much for the help. apply does work for the first situation.
For the second situation, I'm currently using:
temp.a<-function(i,j){
return(G(M[i,],N[j,]))
}
temp.v<-Vectorize(temp.a)
result<-outer(1:nrow(M),1:nrow(N),FUN=temp.v)
Looks pretty good!
Uwe
And I wonder whether there are some other ways to do this.
On Sun, May 18, 2008 at 3:52 PM, Patrick Burns <[EMAIL PROTECTED]> wrote:
You want to use the 'apply' function. S Poetry
has a chapter on higher dimensional arrays that
may be of use to you.
I don't see a good approach for your second
situation other than a double for loop. Unless
G is linear, I think all other solutions will be
equivalent to a double for loop, though the
loops may be hidden.
Patrick Burns
[EMAIL PROTECTED]
+44 (0)20 8525 0696
http://www.burns-stat.com
(home of S Poetry and "A Guide for the Unwilling S User")
Hesen Peng wrote:
Hi all,
I've recently been writing functions which may deal with very large
arrays. And I hope to use *apply functions in the program so that the
code may look nicer and the performance may be better in the following
two situations.
The first situation is:
I'm having an array A with dim(A)==c(m,n,p). And I want to apply a
function F to a group of elements in A like:
1) F is applied to every group of elements like A[i,j,] for all i and j.
or
2) F is applied to every group of elements like A[i,,] for all i, or
A[,j,] for all j.
The result is then expected to be a m*n-dimensional matrix
I'm currently using for loops to do this but I guess there maybe some
*apply functions for arrays which may accomplish this task.
The second situation is:
I'm having two matrix M and N and a function G, which is a function of
two arrays. I want to form a matrix R with dim(R)==c(nrow(M),nrow(N)),
and R[i,j] <- G(M[i,], N[j,]). And I wonder whether I may use some
functions like outer to the matrix.
Thank you very much and have a nice weekend.
______________________________________________
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.
