On 30 Sep 2014, at 03:47 , Jeff Newmiller <[email protected]> wrote:
> library(Matrix)
> result <- newX %*% Diagonal( unlist(beta) )
The code in Matrix does this efficiently, I hope?
Otherwise, sweep() is the traditional ticket:
result <- sweep(newX, 2, unlist(beta), "*")
Some of my students do
t(t(newX) * unlist(beta))
(utilizing recycling of beta) which I think looks horrible, but it does work.
The problem with the original code is that the cbind() reallocates storage
every time a column is added to the result. This can be alleviated by
preallocating. Also note that the double for loop in
for (i in 1: ncol(newX)){
for (j in 1: length(beta)){
Terms <- cbind (Terms,(newX[,i]*beta[j]))
}
}
generates 520*520 columns of pairwise products, which I presume was not the
intention.
--
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: [email protected] Priv: [email protected]
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