Create a matrix with x on the diagonal

rray_diag() creates a matrix filled with x on the diagonal. Use offset to place x along an offset from the diagonal.

rray_diag(x, offset = 0)

Arguments

x	A vector, matrix, array or rray.
offset	A single integer specifying the offset from the diagonal to place x. This can be positive or negative.

Value

A matrix, with x on the diagonal.

Details

No dimension names will be on the result.

Examples

# Creates a diagonal matrix
rray_diag(1:5)
#>      [,1] [,2] [,3] [,4] [,5]
#> [1,]    1    0    0    0    0
#> [2,]    0    2    0    0    0
#> [3,]    0    0    3    0    0
#> [4,]    0    0    0    4    0
#> [5,]    0    0    0    0    5

# Offset `1:5` by 1
rray_diag(1:5, 1)
#>      [,1] [,2] [,3] [,4] [,5] [,6]
#> [1,]    0    1    0    0    0    0
#> [2,]    0    0    2    0    0    0
#> [3,]    0    0    0    3    0    0
#> [4,]    0    0    0    0    4    0
#> [5,]    0    0    0    0    0    5
#> [6,]    0    0    0    0    0    0

# You can also go the other way
rray_diag(1:5, -1)
#>      [,1] [,2] [,3] [,4] [,5] [,6]
#> [1,]    0    0    0    0    0    0
#> [2,]    1    0    0    0    0    0
#> [3,]    0    2    0    0    0    0
#> [4,]    0    0    3    0    0    0
#> [5,]    0    0    0    4    0    0
#> [6,]    0    0    0    0    5    0

# Identity matrix
rray_diag(rep(1, 5))
#>      [,1] [,2] [,3] [,4] [,5]
#> [1,]    1    0    0    0    0
#> [2,]    0    1    0    0    0
#> [3,]    0    0    1    0    0
#> [4,]    0    0    0    1    0
#> [5,]    0    0    0    0    1

# One interesting use case of this is to create
# a square empty matrix with dimensions (offset, offset)
rray_diag(rray(integer()), 3)
#> <rray<int>[,3][3]>
#>      [,1] [,2] [,3]
#> [1,]    0    0    0
#> [2,]    0    0    0
#> [3,]    0    0    0
rray_diag(logical(), 3)
#>       [,1]  [,2]  [,3]
#> [1,] FALSE FALSE FALSE
#> [2,] FALSE FALSE FALSE
#> [3,] FALSE FALSE FALSE