[R-sig-Geo] polygons to arcs?

[Roger Bivand]

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