Re: [R] vectorization help please

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From: Achim Zeileis (zeileis@ci.tuwien.ac.at)
Date: Wed 26 Sep 2001 - 19:22:54 EST 

Message-id: <3BB19E6E.7F38CDF@ci.tuwien.ac.at>

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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