Multiplying elements of a list by rows of a matrix
Clemontina: As you have seen, the answer is yes, but my question is why bother? What's wrong with a for() loop? lapply() should offer no advantage in speed over a loop. Vectorization could, but lapply() is not vectorization. -- Bert
On Sun, Nov 11, 2012 at 8:33 AM, Clemontina Davenport <ckalexa2 at ncsu.edu> wrote:
Hi all, I have the following code: set.seed(1) x1 <- matrix(sample(1:12), ncol=3) x2 <- matrix(sample(1:12), ncol=3) x3 <- matrix(sample(1:12), ncol=3) X <- list(x1,x2,x3) tt <- matrix(round(runif(5*4),2), ncol=4) Is there a way I can construct a new list where newlist[[i]] = tt[i,] %*% X[[i]] without using a for loop? Each element of newlist will be 3 x 1 vector. Thanks -- Tina Alexander
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Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm