[R-sig-Geo] Updating county map in maps package

[Roger Bivand]

On Fri, 8 Feb 2008, John Shonder wrote:

> Does anyone know how to update the map of US counties that is included with
> the maps package? The included map is outdated, and is missing several newer
> counties in various states. The cartographic boundary files from the 2000
> census are available at http://www.census.gov/geo/www/cob/bdy_files.html but
> I find no documentation on how to get these into the maps package.

See the two research reports referred to in for example the help page to 
map():

      Richard A. Becker, and Allan R. Wilks, "Maps in S", _AT&T Bell
      Laboratories Statistics Research Report [93.2], 1993._ <URL:
      http://public.research.att.com/areas/stat/doc/93.2.ps>

      Richard A. Becker, and Allan R. Wilks, "Constructing a
      Geographical Database", _AT&T Bell Laboratories Statistics
      Research Report [95.2], 1995._ <URL:
      http://public.research.att.com/areas/stat/doc/95.2.ps>

both of which are online. You need to break all of the polygons into x0,y0 
and x1,y1 line segments, and clean the topologies, building the databases 
from the input data. It appears that some of the contributed map data has 
not been broken down to elemental components, so there may be an easier 
way. Finding out which output geometries are which is an additional 
challenge.

It might be possible to output the segments or other intermediate text 
files from maptools, contributions welcome.

Roger

>
> I have had success reading the 2000 shape files with maptools, but for
> various reasons I find the maps package more convenient.
>
> I appreciate any assistance, thanks.
>
>

-- 
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