[R] to replace the for loop

[Berend Hasselman]

On 14-12-2013, at 08:01, Arnaud Michel <michel.arnaud at cirad.fr> wrote:

> Hello
> 
> I would like to replace the for loop this below
> 
> T <- as.matrix(T)
> for(i in 1: nrow(TEMP)){
> for(j in 1: nrow(TEMP)){if (i <= j) T[i, j] <- 0 }}
> 

Your code is mangled.
We don’t know what T is.
You refer to TEMP in the for loop but you most likely meant T.

Shouldn’t the second nrow in your for loop be ncol?

> I don't find the function in the doc.

Search with ??uppertri and you’ll find lower.tri in base with sufficient description to have a look at that entry.
Depending on what packages you have, you may find more.


> Thanks in advance for your help.
> 

T[col(T)>=row(T)] <- 0
T[upper.tri(T,diag=TRUE) ] <- 0

Berend


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