polygons to arcs?
On Thu, 15 Mar 2007, Tim Keitt wrote:
Is there an 'sp' function that takes a polygon as its argument and returns a set of line objects corresponding to the arcs in the polygon?
Edzer asked a similar question a couple of days ago - the state of play is not very encouraging: https://stat.ethz.ch/pipermail/r-sig-geo/2007-March/001856.html
Or better yet, a function that given a set of polygons, returns the hull? (ie the set of singleton arcs after applying the polys to arcs function)
But if the problem is to take a union of contiguous polygons, unionSpatialPolygons() in maptools using the gpclib package can do it, but not from the arc topology. Roger
THK
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