[R-sig-Geo] polygons to arcs?

Roger Bivand Roger.Bivand at nhh.no
Thu Mar 15 20:03:36 CET 2007

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:


> 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 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

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