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. -- 彭河森 Hesen Peng http://hesen.peng.googlepages.com/ ______________________________________________ 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.
