[R] Learning to speak R: simple data processing
ej
ejohnso9 at earthlink.net
Fri Jan 11 00:59:29 CET 2013
So, I am just trying to learn R...
Here is a rather contrived example that would be pretty obvious to me in
terms of writing code to loop through elements, but the slick, fast, compact
way of expressing this in R is not obvious to me.
Here's code to generate a simple matrix of data:
> m <- floor(matrix(runif(24, 1, 100), 8, 3))
> m
[,1] [,2] [,3]
[1,] 75 5 15
[2,] 82 79 2
[3,] 72 24 55
[4,] 88 38 3
[5,] 42 82 98
[6,] 38 78 43
[7,] 79 88 60
[8,] 6 89 43
I see how I can get the max on each row as:
> apply(m, 1, max)
[1] 75 82 72 88 98 78 88 89
I want to generate a vector with the column position of each row max.
The whole vector for the matrix shown above would be:
1 1 1 1 3 2 2 2
Is there some easy, straightforward way to compute such a thing short of
looping over the rows and columns of the matrix?
Thanks,
-ej
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