[R-sig-Geo] Help to convert a Polygon in SpatialPolygonsDataFrame

[Roger Bivand]

On Fri, 27 Aug 2010, gianni lavaredo wrote:

> dear Researcher,
>
> it's friday afternoon i am starting to be tired. I don't rememeber the
> method to convert a polygon class in a SpatialPolygonsDataFrame to use
> overlay later. Sorry for destrub with this simple question.
>
> thanks in advance Gianni
>
>
>
> mywindow <- owin(mydata at bbox[1,],mydata at bbox[2,])
>        plot(mywindow, border="red")
>        points(centroid.owin(mywindow),pch=19,cex = 0.7)
>        xy.centr <- as.matrix(data.frame(centroid.owin(mywindow)))
>        # create a circle with the radius equal 1/2 the side of square area
>        big =  disc(radius=100, centre=xy.centr[1,], npoly=4)
>        vert <- vertices(big)
>        # square of 200 x 200 m side
>        r <- as.rectangle(big)
>        plot(r, add=T)
>        vert.r.xy <- as.matrix(data.frame(vertices(r)))
>        vert.r.xy.poligon <- rbind(vert.r.xy,vert.r.xy[1,])
>        p <- Polygon(vert.r.xy.poligon, hole=as.logical(NA))

SP <- SpatialPolygons(list(Polygons(list(p), ID="1")))

should do it.

Roger

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-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no