On May 11, 2010, at 8:36 PM, Q wrote:


Hello,

I am trying to figure out how to do a sum of items within a row.  For
example, I have a data frame something like this:

   A1 B1 ... A2 B2 ...
1   1   4        1  4
2   2   5        2  5
3   3   6        3  6

What I want, is for each row, to get A1 + A2, B1 + B2, etc. which would, perhaps, give me a vector something like this c(2, 8, ... 4, 10 ... 6, 12).

Addition of matrices with the "+" operator should give you a matrix which would have the corresponding sums. Because matrices are really vectors that are read in column order you might need to transpose before you read them out with c().

As always properly formed examples would be appreciated and the form of the appreciation would probably take the form of tested code.

--
David.
--

Does anyone know of a simple way to do this?

Thanks a lot,

Q

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