[geos-devel] troubles with gPolygonize

Masucci, A a.masucci at ucl.ac.uk
Wed Feb 6 02:06:46 PST 2013


Dear Roger,
thanks for your reply and sorry for writing in the wrong mail list.
These are the information you asked me.

> library(rgeos)
Loading required package: sp
rgeos version: 0.2-12, (SVN revision 372)
 GEOS runtime version: 3.3.6-CAPI-1.7.6 
 Polygon checking: TRUE 

> sessionInfo()
R version 2.14.0 (2011-10-31)
Platform: x86_64-pc-mingw32/x64 (64-bit)

Unfortunately I'm not able to open the svn link you sent me

Paolo



________________________________________
From: geos-devel-bounces at lists.osgeo.org [geos-devel-bounces at lists.osgeo.org] on behalf of Roger Bivand [Roger.Bivand at nhh.no]
Sent: 06 February 2013 09:19
To: geos-devel at lists.osgeo.org
Subject: Re: [geos-devel] troubles with gPolygonize

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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