[R] Saving run time in loop

[vincent.deluard]

Hi r users,

I am trying to compute the "moving variance" of a large matrix. I now use a
loop but I am looking for a faster solution. Here is a sample of the code.

Source= matrix(rnorm(400),ncol=100)
variances= matrix(rep(NA,4*100),ncol=100)

for (i in 1:80) {variances[,i]=apply(Source[,i:(i+80)],1,var)}

any idea? Many thanks in advance.


Vincent.

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