e.g.
# x is a gpc.poly object
as.Polygons.gpc.poly <- function(x, ID) {
thisPolys <- lapply(get.pts(x), function(p) {
Polygon(rbind(as.matrix(cbind(p$x,p$y)),c(p$x[1],p$y[1])),
hole=p$hole)
})
Polygons(thisPolys, ID)
}
This works except if the gpc.poly is empty. `Polygons` fails if passed
an empty list().
Felix
On 8/9/07, Felix Andrews <[EMAIL PROTECTED]> wrote:
> Hmm
>
> I'm trying to work with gpclib, converting to and from the sp classes.
> I don't know what is/was in the package spgpc, but it is no longer
> available:
> > install.packages("spgpc", repos=rSpatial)
> Warning: unable to access index for repository
> http://r-spatial.sourceforge.net/R/bin/windows/contrib/2.5
>
> The page http://r-spatial.sourceforge.net/xtra/xtra.RHnw.html says:
> "the functionality described here has been included in packages rgdal,
> naptools, and spgrass6, now all on CRAN. This page is maintained for
> documentary purposes only, and most of the examples shown here are the
> examples used in the released packages."
>
> where i'm guessing "naptools" should be "maptools".
> But I can not find a method to coerce between "gpc.poly" and
> "Polygons" classes. Not that it is difficult to manually... just
> wondering.
>
> Felix
>
> --
> Felix Andrews / 安福立
> PhD candidate
> Integrated Catchment Assessment and Management Centre
> The Fenner School of Environment and Society
> The Australian National University (Building 48A), ACT 0200
> Beijing Bag, Locked Bag 40, Kingston ACT 2604
> http://www.neurofractal.org/felix/
> voice:+86_1051404394 (in China)
> mobile:+86_13522529265 (in China)
> mobile:+61_410400963 (in Australia)
> xmpp:[EMAIL PROTECTED]
> 3358 543D AAC6 22C2 D336 80D9 360B 72DD 3E4C F5D8
>
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