[R] How extract the names of ID in SpatialPolygons object

[Roger Bivand]

On Fri, 30 Dec 2005, fernando espindola wrote:

> Hi dear user,
> 
> Anybody can tell me how extract the names of ID in  SpatialPolygons  
> object,  I am try to link a data frame attributes with spatial polygons, 
> but the row names of data frame is not the same that ID poligons.

The most generic way is to extract the "polygons" slot from your object 
and then the "ID" from each member "Polygons" in turn - using sapply 
because you want a character vector returned, one ID for each list member:

sapply(slot(mySpatialPolygons, "polygons"), function(x) slot(x, "ID"))

but there is an access function too:

getSpPPolygonsIDSlots()

which is just the above with a name.

Roger


> 
> Thank for all
> 
> Fernando
> 
> 	[[alternative HTML version deleted]]
> 
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-- 
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