threshold matrix

Thanks a lot.
I finally used

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

as I noticed that this one line

M2 <- as.numeric( M[] < thresh )
vectorizes my matrix.

One more question I have two matrices that only differ slightly.  
What will be the easiest way to compare and find the cells that are  
not the same?

Best Regards
Alex

--- On Fri, 4/29/11, David Winsemius <dwinsemius at comcast.net> wrote:

From: David Winsemius <dwinsemius at comcast.net>
Subject: Re: [R] threshold matrix
To: "Alaios" <alaios at yahoo.com>
Cc: R-help at r-project.org
Date: Friday, April 29, 2011, 2:57 PM

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