[geos-devel] troubles with gPolygonize

[Roger Bivand]

This is a question about the use of the R package rgeos, which provides GEOS
for sp classes. Consequently, this list is not a good choice; the R-sig-geo
list would have been better. You have also not provided version information
on rgeos, GEOS, or R; the two first are shown when rgeos is loaded, the
latter as output from sessionInfo().

The problem was an assumption in the R code providing IDs for the output
objects, not in GEOS. A fix has been committed to the R-Forge SVN repository
for rgeos, together with your case in the examples for the function. If you
can, please check out the source:

svn checkout svn://svn.r-forge.r-project.org/svnroot/rgeos/

and report back on whether the fix also works for your real use case.

Roger


Masucci, A wrote
> Hi,
> gPolygonize doesn't work with some simple geometries.
> Here is an example:
> 
>> LS = list(
> + readWKT("LINESTRING (425963 576719, 425980 576703)"),
> + readWKT("LINESTRING (425963 576719, 425882 577073)"),
> + readWKT("LINESTRING (425980 576703, 426082 577072)"),
> + readWKT("LINESTRING (425882 577073, 426082 577072)"),
> + readWKT("LINESTRING (426138 577068, 426082 577072)"),
> + readWKT("LINESTRING (426138 577068, 426420 577039)"),
> + readWKT("LINESTRING (426420 577039, 426554 576990)"),
> + readWKT("LINESTRING (426751 576924, 426776 576823)"),
> + readWKT("LINESTRING (426751 576924, 426783 576919)"),
> + readWKT("LINESTRING (426751 576924, 426714 576953)"),
> + readWKT("LINESTRING (426776 576823, 426783 576919)"),
> + readWKT("LINESTRING (426658 576966, 426554 576990)"),
> + readWKT("LINESTRING (426658 576966, 426667 577031)"),
> + readWKT("LINESTRING (426658 576966, 426714 576953)"),
> + readWKT("LINESTRING (426667 577031, 426714 576953)")
> + )
>> gPolygonize(LS)
> 
> Traceback:
>  1: .Call("rgeos_polygonize", .RGEOS_HANDLE, splist, id, p4s, getCutEdges,    
> PACKAGE = "rgeos")
>  2: gPolygonize(LS)
> Error in gPolygonize(LS) : caught access violation - continue with care
> 
> I hope you can help me
> Kindest regards
> 
> Paolo
> 
> _______________________________________________
> geos-devel mailing list

> geos-devel at .osgeo

> http://lists.osgeo.org/mailman/listinfo/geos-devel





-----
Roger Bivand
NHH Norwegian School of Economics, Bergen, Norway
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