R: subtraction of elements of a matrix from the elements of another matrix
equation-solving, matrix, r
Solution
normal operators like `+`, `-`, `*`, `/` and `^` do element wise operations. So simply `(r - nr)^2/6` will do the trick for you.
r
## [,1] [,2] [,3]
## [1,] 2 2 2
## [2,] 2 2 2
## [3,] 2 2 2
nr
## [,1] [,2] [,3]
## [1,] 3 3 3
## [2,] 3 3 3
## [3,] 3 3 3
r * nr
## [,1] [,2] [,3]
## [1,] 6 6 6
## [2,] 6 6 6
## [3,] 6 6 6
r - nr
## [,1] [,2] [,3]
## [1,] -1 -1 -1
## [2,] -1 -1 -1
## [3,] -1 -1 -1
(r - nr)^2/6
## [,1] [,2] [,3]
## [1,] 0.1666667 0.1666667 0.1666667
## [2,] 0.1666667 0.1666667 0.1666667
## [3,] 0.1666667 0.1666667 0.1666667
Problem
I am trying to apply an equation to two matrices. Since I am a beginner R user, it seems very difficult to me. I would be greatful if you could give me some advice. I have two similarity matrices: ``` > r [,1] [,2] [,3] [,4] [,5] [,6] [1,] 0 4 2 2 5 5 [2,] 4 0 8 3 3 2 [3,] 2 8 0 4 4 3 [4,] 2 3 4 0 0 3 [5,] 5 3 4 0 0 5 [6,] 5 2 3 3 5 0 > nr [,1] [,2] [,3] [,4] [,5] [,6] [1,] 0 4 7 2 4 3 [2,] 4 0 5 2 3 2 [3,] 7 5 0 3 2 2 [4,] 2 2 3 0 7 2 [5,] 4 3 2 7 0 5 [6,] 3 2 2 2 5 0 ``` And I wolud like to apply to these the following: ``` sum((r[i,j]-nr[i,j])^2)/6 ``` My great problem is to extract elements of `nr` from the elements `r`. If I substitute `nr[i,j]` with a number, for example `0.4` then the following works perfectly: ``` s<-numeric() for (i in 1:nrow(r)) { for (j in 1:ncol(r)) { s[k]<-sum((r[i,j]-0.4)^2)/6 } } > s [1] 0.02666667 ``` But I can't figure out how could I modify this code to solve the original problem. I would appreciate any kind of help/suggestion. Thanks!