R help - Sep 2009 - Fastest Way to Divide Elements of Row With Its RowSum

I have a data frame (dat). What I want to do is for each row,
divide each row  with the sum of its row.

The number of row can be large > 1million.
Is there a faster way than doing it this way?

datnorm;
for (rw in 1:length(dat)) {
    tmp <- dat[rw,]/sum(dat[rw,])
    datnorm <- rbind(datnorm, tmp);
}


- G.V.

At 2:40 PM +0900 9/17/09, Gundala Viswanath wrote:
>I have a data frame (dat). What I want to do is for each row,
>divide each row  with the sum of its row.
>
>The number of row can be large > 1million.
>Is there a faster way than doing it this way?
>
>datnorm;
>for (rw in 1:length(dat)) {
>     tmp <- dat[rw,]/sum(dat[rw,])
>     datnorm <- rbind(datnorm, tmp);
>}
>
>
>- G.V.

datnorm <- dat/rowSums(dat)

this will be faster if dat is a matrix rather than a data.frame.

Bill

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