[R] vectorization help please

[Uwe Ligges]

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)
> }


 im * (-1)^(row(im) + col(im))

Uwe
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !)  To: r-help-request at stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._