[Fwd: Excluding data with apply]

Dear all,

I've got many responses to my initial question, which is stated below. 
However, from those responses it has become clear that I need to 
rephrase my problem. All responses dealt with subscripting the data 
matrix before 'apply' is run on it. But this is not want I wanted to do.
'apply' cycles through rows or columns of a matrix, and runs a function 
on each row or column individually. Now, instead of focusing on each 
individual row or column, I want to get rid of these rows or columns, 
and run the function on the remaining matrix.
I could do this with a for loop, such as:

x<-matrix(rnorm(100),20,5)
for (i in 1:ncol(x)) print(mean(x[,-i]))

But for more complex problems this becomes tedious...

Any ideas would be highly appreciated, Christian

Dear all,

'Apply' is a great thing for running functions on rows or columns of a 
matrix:

X <- rnorm(20, mean = 0, sd = 1)
dim(X) <- c(5,4)
apply(X,2,sum)

Is there a way to use apply for excluding rows or columns from a 
matrix to run functions on the remaining rows or columns? I know, I 
could do this with a 'for' loop, but 'apply' would be much easier and 
quicker, and require less programming...

Cheers, Christian