Divide each element in a matrix by one element in R

Asked Sep 16 '19 at 11:56

Active Sep 16 '19 at 12:01

Viewed 120 times

Consider the following matrix:

matrix <- matrix(1:9, nrow = 3, ncol = 3)

     [,1] [,2] [,3]
[1,]    1    4    7
[2,]    2    5    8
[3,]    3    6    9

For the two first columns ([,1] and [,2]), I want to divide each element until row [3,] with the number in row [3,]. That is, I want to get the following matrix:

     [,1] [,2]
[1,]  1/3  4/6 
[2,]  2/3  5/6

How do I do that in R?

edited Sep 16 '19 at 12:01

asked Sep 16 '19 at 11:56

Michael

Do you mean " with the number in *raw* [3,]" ? Column 3 is never used in you output, it's like you divide raw 1 and 2 bay raw 3 – Chelmy88 Sep 16 '19 at 11:59
Your logic and end result do not align? – boski Sep 16 '19 at 11:59
Sorry, my mistake. I have corrected the question now. – Michael Sep 16 '19 at 12:02
`m <- matrix(1:9, nrow = 3, ncol = 3); sweep(m, 2, '/', STATS=m[3,])` or `sweep(m[-3,], 2, '/', STATS=m[3,])` – jogo Sep 16 '19 at 12:02
Try: `t(t(matrix[1:2,1:2]) / matrix[3,1:2])` – GKi Sep 16 '19 at 12:03
1

You can do `sweep(mat[1:2, ], 2, mat[3, ], "/")`. – tmfmnk Sep 16 '19 at 12:03

Divide each element in a matrix by one element in R

0 Answers0