
I have the following scenario:

> m <- matrix(1:4, ncol=2)
> m
      [,1] [,2]
[1,]    1    3
[2,]    2    4
> apply(m, 2, sum)
[1] 3 7
> apply(m, 1, sum)
[1] 4 6

So I can apply to rows *or* columns. According to the documentation 
(?apply)

MARGIN a vector giving the subscripts which the function will be applied 
over. E.g., for a matrix 1 indicates rows, 2 indicates columns, c(1, 2) 
indicates rows and columns. Where X has named dimnames, it can be a 
character vector selecting dimension names.


But I get the following results:

> apply(m, c(1,2), sum)
      [,1] [,2]
[1,]    1    3
[2,]    2    4

How am I to interpret this result?

Thank you.

Kevin

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