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.biv...@nhh.no
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