Column-by-column division
Why not use standard matrix multiplication which is straightforward here: x %*% diag(1/s) HTH, Eric On Wed, Mar 3, 2021 at 7:13 AM Harold Doran <
harold.doran at cambiumassessment.com> wrote:
To make sure the scalar is used instead of using the recycled vector s, maybe like this x <- matrix(1:20, nrow=10) s <- c(1,2) sapply(1:2, function(i) x[,i]/s[i]) -----Original Message----- From: R-help <r-help-bounces at r-project.org> On Behalf Of Steven Yen Sent: Wednesday, March 3, 2021 6:00 AM To: R-help Mailing List <r-help at r-project.org> Subject: [R] Column-by-column division I have a 10 x 2 matrix x. Like to divide the first column by s[1] and second column by s[2]. The following lines work but are clumsy. Any idea? Thanks.
> x
[,1] [,2] [1,] 1 11 [2,] 2 12 [3,] 3 13 [4,] 4 14 [5,] 5 15 [6,] 6 16 [7,] 7 17 [8,] 8 18 [9,] 9 19 [10,] 10 20
> s
[1] 1 2
> t(t(x)/s)
[,1] [,2] [1,] 1 5.5 [2,] 2 6.0 [3,] 3 6.5 [4,] 4 7.0 [5,] 5 7.5 [6,] 6 8.0 [7,] 7 8.5 [8,] 8 9.0 [9,] 9 9.5 [10,] 10 10.0
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