[R-sig-Geo] How can I convert a "SpatialPolygons" object, to a "polylist"?

[Patrick Giraudoux]

>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sat, 02 May 2009 22:52:36 -0500
> From: Jim Burke <j.burke at earthlink.net>
> Subject: [R-sig-Geo] How can I convert a "SpatialPolygons" object to a
> 	"polylist"?
> To: r-sig-geo at stat.math.ethz.ch
> Message-ID: <49FD1504.7060101 at earthlink.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> How can I convert a "SpatialPolygons" object to a "polylist" 
>
> I have a file read in with "readShapePoly". This contains the polygon
> long lats in a slot called "coords". I want to use the package "splancs"
> "inout" function which works according to the doc with polygon data sets.
> An example Map2Poly which works with "inout" lists itself as a class 
> "polylist".  
>
> Thanks,
> Jim Burke


if your SpatialPolygons name is e.g. myObject

lapply(myObject at polygons, function(x) x at Polygons[[1]]@coords)

should make it in the very simple case (the most common too anyway)
where each attribute line corresponds to one single polygon. It will
provide you with a list whose elements will be the coordinates of each
polygon.

More complex cases are a bit more difficult to handle

Patrick