[R] Efficent way to create an nxn upper triangular matrix of one's

[Sundar Dorai-Raj]

Try

x <- diag(n)
x[upper.tri(x)] <- 1

On Wed, Feb 11, 2009 at 1:22 PM, Dale Steele <dale.w.steele at gmail.com> wrote:
> The code below create an nxn upper triangular matrix of one's.  I'm
> stuck on finding a more efficient vectorized way - Thanks.  --Dale
>
> n <- 9
> data <- matrix(data=NA, nrow=n, ncol=n)
> data
> for (i in 1:n) {
>    data[,i] <- c(rep(1,i), rep(0,n-i))
> }
> data
>
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