Diagonal Indices of a Matrix

Returns a matrix of logicals the same size of a given matrix with entries 'TRUE' in the upper triangle close to the diagonal.

diag.ind(x, n = 1, diag = TRUE)

Arguments

x	a matrix.
n	the number of elements from the diagonal to include.
diag	logical. Should the diagonal be included?

Details

Basic function useful for masking elements close to the diagonal of a given matrix.

Value

Returns a matrix of logicals the same size of a given matrix with entries 'TRUE' in the upper triangle close to the diagonal.

References

Grant, B.J. et al. (2006) Bioinformatics 22, 2695--2696.

Author

Barry Grant

See also

diag, lower.tri, upper.tri, matrix

Examples

diag.ind( matrix(,ncol=5,nrow=5), n=3 )
#>       [,1]  [,2]  [,3]  [,4]  [,5]
#> [1,]  TRUE  TRUE  TRUE FALSE FALSE
#> [2,] FALSE  TRUE  TRUE  TRUE FALSE
#> [3,] FALSE FALSE  TRUE  TRUE  TRUE
#> [4,] FALSE FALSE FALSE  TRUE  TRUE
#> [5,] FALSE FALSE FALSE FALSE  TRUE