[R-sig-Geo] Error message in rgeos

[Leonardo Monasterio]

Dear Colin,

Thank you very much. I've uploaded shapefile to:
http://dl.dropbox.com/u/116353/OD87.zip

Yours,
Leonardo.

On Thu, Apr 7, 2011 at 6:39 PM, Colin Rundel <rundel at gmail.com> wrote:
>
>> I am getting the following error message when I try:
>>
>>> lineborder<-gBoundary(map1)
>> Erro em TopologyFunc(spgeom, id, byid, "rgeos_boundary") :
>>  IllegalArgumentException: Operation not supported by GeometryCollection
>>
>> map1 is a polygon created from a shape file.
>>
>> Also I get:
>>> gIsSimple(map1)
>> Erro em RGEOSUnaryPredFunc(spgeom, byid, "rgeos_issimple") :
>>  IllegalArgumentException: This method does not support
>> GeometryCollection arguments
>>> gIsValid(map_outer_ring)
>> [1] TRUE
>
> For some reason when Rgeos is attempting to convert your sp object it is using a GeometryCollection type instead of a Polygon or Multipolygon type. Currently the GEOS library does not support GeometryCollection types with either gBoundary or gIsSimple and some of the other functions as well.
>
> You can try both functions with byid=TRUE which will then run the GEOS function on each sub element of your sp object and will either return a single sp object or list of sp objects depending on the compatibility of the returned values.
>
> If you can host the shapefile you are using somewhere and provide a link, I can look into why Rgeos is treating it as a GeometryCollection.
>
> -Colin