[R-sig-Geo] Status of gpclib license (was: Alternate methods: Polygon Algebra / Polygon Overlay with R Spatial objects..)

[Nicholas Lewin-Koh]

Hi Roger,
I thought I remembered that at some point you had contacted the author
of gpclib and gotten permission to release the package under gpl. Has
that changed or is senility completely catching up with me.

Nicholas


> Date: Fri, 15 Jan 2010 20:00:30 +0100 (CET)
> From: Roger Bivand <Roger.Bivand at nhh.no>
> To: rick reeves <reeves at nceas.ucsb.edu>
> Cc: "r-sig-geo at stat.math.ethz.ch" <r-sig-geo at stat.math.ethz.ch>
> Subject: Re: [R-sig-Geo] Alternate methods: Polygon Algebra / Polygon
> 	Overlay with R Spatial objects..
> Message-ID: <alpine.LRH.2.00.1001151932080.18465 at reclus.nhh.no>
> Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII
> 
> On Fri, 15 Jan 2010, rick reeves wrote:
> 
> > Hello List:
> >
> > I have been reviewing techniques within R for performing the GIS-like 
> > operation 'polygon algebra' (computing the union and intersection of 
> > polygons within two SpatialPolygonDataFrame objects). The goal is to 
> > combine two polygon data frames, to produce a new polygon data frames 
> > that contain the union or intersection of the two input sets.
> >
> > Thus far, the only method that I have found for this is the 
> > combinePolys() method within the PBSmapping package. The PBSmapping 
> > routines work well, but require the transformation out of the 
> > SpatialXXXDataFrame classes.
> 
> For union, aka dissolve, see unionSpatialPolygons() in maptools. Perhaps 
> better, don't look yet. The underlying problem is the license of the 
> gpclib package, which should be avoided. The reason for attention to 
> package licenses is that CRAN is getting very large, and taking 
> responsibility for distributing non-free software through package 
> dependencies needs to be automated. So GPL and other free packages should 
> not depend on or suggest non-free packages, because users (including 
> commercial users) may not be aware that they are using packages with 
> non-free licences. Some of these users already block the installation of 
> free packages with "upstream" non-free dependencies, and more will do so 
> in the future.
> 
> One solution is the R-Forge rgeos package, which I'm working on.
> 
> https://r-forge.r-project.org/projects/rgeos/
> 
> Before long, again thanks to Uwe Ligges and others, we should have a 
> working production line for Windows binary packages with GEOS 3.1.1 
> included. Linux distributions have binaries or can install from source; 
> OSX has a Kyngchaos framework to handle the external dependency on GEOS.
> 
> rgeos has unionSpatialPolygonsGEOS(), which, when rgeos reaches CRAN,
> will 
> be used by maptools in unionSpatialPolygons() if rgeos is available.
> 
> GEOS has the necessary functions to do what you would like, but someone 
> has to write the R and C code and add it to rgeos. The current 
> SpatialLinesIntersections() function returns a SpatialPointsDataFrame 
> object with the IDs if the intersecting lines, but more is needed for 
> SpatialPolygons intersection. The handling of the data frame variables is 
> far from obvious too - just copying across count or rate variables isn't 
> appropriate. Most likely the handling of the data slots would have to be 
> done by hand for the new SpatialPolygons objects based on the
> intersecting 
> ID values.
> 
> R-Forge has the possibility for new developers to join projects ...
> 
> Hope this helps,
> 
> Roger
> 
> >
> > The overlay() method within sp seems like the best routine for this job as it
> > performs intersection operations on pairs of Spatial objects, but it
> > does not appear to operate on two SpatialPolygonDataFrame objects.
> > So I have not tried to use it for this.
> >
> > Do other packages contain polygon algebra routines that operate on the 
> > Spatial classes?
> > If not, are there any alternatives to the PBSmapping methods?
> >
> > Thanks,
> > Rick R
> >
> >
> >
> >
> 
> -- 
> Roger Bivand
> Economic Geography Section, Department of Economics, Norwegian School of
> Economics and Business Administration, Helleveien 30, N-5045 Bergen,
> Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
> e-mail: Roger.Bivand at nhh.no
> 
> 
> 
> ------------------------------
> 
> _______________________________________________
> R-sig-Geo mailing list
> R-sig-Geo at stat.math.ethz.ch
> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
> 
> 
> End of R-sig-Geo Digest, Vol 77, Issue 13
> *****************************************