On Wed, Jun 9, 2010 at 3:24 PM, Edzer Pebesma
<edzer.pebe...@uni-muenster.de> wrote:
> The example provided by Matt assumes that each polygon consists of a
> single ring, and doesn't have islands, lakes etc. The function below
> pasts all coordinates to a single 2-column matrix. For clarity's sake, I
> avoided nested sapply's.
>
> library(maptools)
> xx <- readShapePoly(system.file("shapes/sids.shp", package="maptools")[1],
> IDvar="FIPSNO", proj4string=CRS("+proj=longlat +ellps=clrk66"))
> allcoordinates = function(x) {
> ret = NULL
> polys = x...@polygons
> for(i in 1:length(polys)) {
> pp = polys[[...@polygons
> for (j in 1:length(pp))
> ret = rbind(ret, coordinates(pp[[j]]))
> }
> ret
> }
> q = allcoordinates(xx)
>
> # check:
> plot(xx)
> lines(q, col='blue')
And that's basically what fortify does, except it covers a few more cases.
Hadley
--
Assistant Professor / Dobelman Family Junior Chair
Department of Statistics / Rice University
http://had.co.nz/
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