[R-sig-Geo] Buffer series

[Barry Rowlingson]

On Tue, Jul 12, 2011 at 11:00 AM, te_är <tamara_em at hotmail.com> wrote:
> I'd like to automatically create buffers to points with a series of different
> radii.
> I'd intuitively tried like that (but I realized while writing that it cannot
> work):
>
> for (i in 1:10)
> {
> west_buf[i]<-gBuffer(west,byid=T,id=NULL,width=i,capStyle="ROUND")
> cent_buf[i]<-gBuffer(cent,byid=T,id=NULL,width=i,capStyle="ROUND")
> east_buf[i]<-gBuffer(east,byid=T,id=NULL,width=i,capStyle="ROUND")
> }

 What makes you think it cannot work? I think your only problem here
is storing the result in a vector rather than a list.

> Is there a possibility to create a series of buffers of different size, i.e.
> kind of
> looping the width?

Like this:

 > pts=cbind(runif(10),runif(10))
 > pts=SpatialPoints(pts)
 > plot(pts)
 > bufs=list() # store results as elements of a list
 > for(i in 1:10){bufs[[i]]=gBuffer(pts,byid=TRUE,id=NULL,width=i/10,capStyle="ROUND")}
 > plot(bufs[[10]])
 > plot(bufs[[9]],add=TRUE,lty=2)

 You can store almost anything in a list.

Barry