R: applying function over matrix and keeping matrix dimensions

Question

So I want to apply a function over a matrix in R. This works really intuitively for simple functions:

> (function(x)x*x)(matrix(1:10, nrow=2))
 [,1] [,2] [,3]         


        

Answer 1

For this specific example you can just do something like this

> # Create some fake data
> mat <- matrix(1:16, 4, 4)
> # Set all elements divisible by 3 to NA
> mat[mat %% 3 == 0] <- NA
> # Add 1 to all non NA elements
> mat <- mat + 1
> mat
     [,1] [,2] [,3] [,4]
[1,]    2    6   NA   14
[2,]    3   NA   11   15
[3,]   NA    8   12   NA
[4,]    5    9   NA   17