[R-sig-Geo] handling of 3D polylines or 3D polygons in R

[Manuel Campagnolo]

I realized that sp classes SpatialPolygons and SpatialLines do not 
handle Z coordinates. Are there alternatives for spatial geometries 
with  Z coordinates? I would like to read and write 3D line and polygon 
shapefiles (that represent roads, streams, ridges or basins) and analyse 
them in R.

Thanks in advance for suggestions,
Manuel

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Manuel Campagnolo
http://math.isa.utl.pt/~mlc/