Set or get matrix value at index vector

This function allows to access matrix values by passing indices as vector

at(mat, idx)

at(mat, idx) <- value

Arguments

mat	matrix
idx	two-element integer vector
value	a value to be assign at index

Value

`at` function: value from matrix at index idx

Examples

mat <- matrix(0, 3, 3)
idx <- c(1, 2)
# Typically, given matrix and row-column indices as two-element vector, we should do it like this:
mat[idx[1], idx[2]]
#> [1] 0
mat[idx[1], idx[2]] <- 8
# Using `at`, we can do it simplier!
at(mat, idx)
#> [1] 8
at(mat, idx) <- 7
mat
#>      [,1] [,2] [,3]
#> [1,]    0    7    0
#> [2,]    0    0    0
#> [3,]    0    0    0
at(mat, idx)
#> [1] 7