[R-sig-Geo] thinning a SpatialPolygonsDataFrame

[Roger Bivand]

On Wed, 18 Nov 2009, Michael Friendly wrote:

> The Guerry package contains two maps of france (gfrance, gfrance85) which are 
> quite detailed and large in size (~900K).
> In writing a vignette for the package, there are quite a few figures that use 
> the map multiple times in a layout, and
> consequently result in huge file sizes for the .PDF files created.  For these 
> purposes, the map need not be nearly
> so detailed.
>
> I'm wondering if there is a facility to "thin" the map by drawing it at a 
> lower density of lines in the polygon regions.
> When I was working with SAS, there was a GREDUCE procedure that did this 
> nicely.

Not yet - the interface to JTS in the cshapes package only uses line 
generalisation on the built-in data set. I'm looking at ways of 
interfacing GEOS, which does offer this, but it will take a little time to 
complete. For a quicker solution, there are facilities in GRASS in 
v.generalize.

Roger

>
> thanks,
> -Michael
>
>

-- 
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