[R-sig-Geo] Extract part(s) of SpatialPolygonsDataFrame

[sylvain willart]

Hello,

I have an .RData file which is a SpatialPolygonsDataFrame a France,

I only need, for now, to work on two areas: Burgundy and Centre,

I would like to extract those two areas from the France file,

I tried, naïvely,
Centre <- France[France$NAME_1=="Centre", ]

but it didn't work out,
(NAME_1 is the variable where are stored the names of the French Regions)

any idea ?

Sylvain
PS: I found quite a lot of information on points, ploygons, or lines,
but few on spatialpolygonsdataframe besides they are "a set of spatial
polygons", Any reference on their inside structure ?