[R] map of a country and its different geographical levels

[Roger Bivand]

On Sat, 7 Nov 2009, hadley wickham wrote:

>> If readShapePoly() (deprecated - use readShapeSpatial() instead) says that
>> the data are not polygons, then they are not. If you want to fill
>> administrative boundaries polygons, you need polygons, not lines. The source
>> you are using is based on OpenStreetMaps, so more likely to be lines, and as
>> the website says, not authorised. You need to locate an appropriate source
>> of boundary data first for your geographical features of interest. There are
>> very few national mapping agencies that make these data available free (the
>> US led on this, some others are understanding too, slowly).
>
> http://gadm.org/country seems to provide this data for very many
> countries - and in sp objects too!

Right, but ... the first one I tried (Irish Republic) had very detailed 
coastlines, very coarse county boundaries, and (worse) the county 
boundaries did not match paper maps, atlases, or Google Earth - counties 
which do not share boundaries in other sources do in GADM, and vice-versa. 
There is an authority/metadata problem - the maps look plausible and 
things may be more-or-less where they should be, but that's all you get, 
I'm afraid. I've tried to report the discrepancy without success so far. I 
really hope that the case I hit is an exception - displaying the 
boundaries on GE should help clear things up for users.

Roger

>
> Hadley
>
>
>

-- 
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