[R-sig-Geo] polygon adjacency testing

Barry Rowlingson b.rowlingson at lancaster.ac.uk
Fri Aug 13 18:14:41 CEST 2010

On Fri, Aug 13, 2010 at 4:59 PM, Nikhil Kaza <nikhil.list at gmail.com> wrote:
> I havent looked at poly2nb code, but would eliminating polygons from the
> polygon list based on area, perimeter  or ratio of these two, before
> constructing the neighbour list work? This would be similar, not identical,
> to eliminate in ArcInfo.
> http://webhelp.esri.com/arcgisdesktop/9.2/index.cfm?TopicName=Eliminate%20%28Data%20Management%29

 That's okay for general cleanups of slivers etc, but it wont catch
other problems that might manifest themselves via adjacency. My
substantive problem uses polygon adjacency in its model, so I was
hoping for a way of assessing the correctness of the adjacency graph.

 I'm pretty sure I can do it with LinesIntersections from rgeos now,
its just a bit of a grind to get rid of all the intersections from
coincident endpoints. nb2lines is also useful.


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