Helpers for working with matrices

Get matrix indices

The matrix_indices() function returns matrix indices as character:

M <- diag(3)
matrix_indices(M)
#> [1] "11" "21" "31" "12" "22" "32" "13" "23" "33"
matrix_indices(M, "M_")
#> [1] "M_11" "M_21" "M_31" "M_12" "M_22" "M_32" "M_13" "M_23" "M_33"
matrix_indices(M, "M_", TRUE)
#> [1] "M_21" "M_31" "M_12" "M_32" "M_13" "M_23"