[R] threshold matrix

[David Winsemius]

On Apr 29, 2011, at 9:37 AM, Alaios wrote:

> Dear all,
> I have a quite big matrix which I would like to threshold.
> If the value is below threshold the cell should be zero
> and
> if the value is over threshold the cell should be one

M2 <- M
M2[M < thresh] <- 0
M2[M >= thresh] <- 1

or perhaps simply:

M2 <- as.numeric( M[] < thresh )
>
> One really simple way to do that is two have a nested loop and check  
> cell by cell.
>
> The problem is that this seems to be really time consuming and  
> ineficient.
>
> What do you suggest me to try out?

-- 

David Winsemius, MD
West Hartford, CT