apply on rows and columns?
It's the same as what you began with -- and that's because you broke it down by columns and rows and took the sum of everything that resulted. I.e., sum(m[1,1]) sum(m[2,1]) sum(m[1,2]) sum(m[2,2]) and put them back together. Michael
On Wed, Nov 16, 2011 at 3:13 PM, <rkevinburton at charter.net> wrote:
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 ? ? ? ?[[alternative HTML version deleted]]
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