[R-sig-Geo] Merging spatial polygons
Roger.Bivand at nhh.no
Fri Jun 14 09:49:23 CEST 2013
On Thu, 13 Jun 2013, John Tomkinson wrote:
> I'm looking to merge spatial polygons within a spatial polygon object. I
> used to do this with the union spatial polygons command :
> neighbourhoods<-unionSpatialPolygons(city, neighbourhood$ID,
> threshold=NULL, avoidGEOS=FALSE, avoidUnaryUnion=FALSE)
> But now having gpclib issues, my question is how would I do this with
> the rgeos package? I can't seem to get the gUnion function to work.
If rgeos is available, unionSpatialPolygons() will use that rather than
gpclib, so actually runs: gUnaryUnion(spgeom=city,
id=as.character(neighbourhood$ID)) in your case. What does rgeosStatus()
say with maptools loaded?
Always provide full details of error messages, best a reproducible example
with a built-in data set, and always the output of sessionInfo().
> Thanks in advance,
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