[R] vectorization help please
Achim Zeileis
zeileis at ci.tuwien.ac.at
Wed Sep 26 11:22:54 CEST 2001
Bill Simpson wrote:
>
> What is a smarter way of doing:
>
> for(i in 1:xn)
> for(j in 1:yn)
> {
> im2[i,j]<- im[i,j]* (-1)^(i+j)
> }
Maybe something like
im * (-1)^(row(im)+col(im))
Hope that helps
Z
> Thanks!
>
> Bill
>
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