[R-sig-Geo] Define bordres in geoR using a shape file??

[Roger Bivand]

On Wed, 12 Dec 2007, Luca Moiana wrote:

> Hello everyone,
>
> I’m moving
> to R to do gesostatistics and today’s problem is:
>
> I have a shp file of the region I’m considering and I want to define the 
> value “borders=” in the expression as.geodata.
>
> I imported the shapefile using maptools and I now have a spatial object, 
> I think I have to convert the spatial object in a 2 columns matrix but I 
> have no clue.
>

Please quote a short extract of your commands, and show what sessionInfo() 
says, both help. My reading of the code suggests that if the class of your 
polygons object is "SpatialPolygons", you can pass this through borders=, 
and the internal point-in-polygon function will find which locations= 
points fall inside the polygons. The borders= argument can also be a 
matrix, but it is turned into a SpatialPolygons object internally. Use 
as(<>, "SpatialPolygons") to coerce to SpatialPolygons.

An alternative is to overlay() your input locations (SpatialGrid object) 
with the SpatialPolygons object to make a SpatialPixels object, then take 
coordinates() of that object and pass them through locations=.

Roger

>
> Any help is greatly welcome!!
>
> Luca
>

-- 
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