[R] vectorization help please

[Achim Zeileis]

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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