[R-sig-Geo] map to shapefile with projection info

[Sebastian P. Luque]

On Wed, 06 Dec 2006 14:00:38 -0600,
"Sebastian P. Luque" <spluque at gmail.com> wrote:

> On Wed, 6 Dec 2006 20:28:42 +0100 (CET),
> Roger Bivand <Roger.Bivand at nhh.no> wrote:

[...]

>> names <- sapply(slot(canada_sp, "polygons"), function(i) slot(i, "ID"))
>> canada_spdf <- SpatialPolygonsDataFrame(canada_sp,
>>   data=data.frame(names=names, row.names=names))
>> writeOGR(canada_spdf, dsn=".", layer="canada", driver="ESRI Shapefile")
>> list.files(pattern="canada")

I searched on the maps and mapdata packages for the missing datum, but
only found this:


,-----[ *help[R](map)* (lines: 54 - 59) ]
| projection: character string that names a map projection to use. See
|           'mapproject' (in the 'mapproj' library). The default is to
|           use a rectangular projection with the aspect ratio chosen so
|           that longitude and latitude scales are equivalent at the
|           center of the picture. 
`-----


where I think mapproj code has been transferred to rgdal.  How can we
create a datum from this information?  Thanks once again.


-- 
Seb