[R-sig-Geo] flip SpatialGridDataFrame across axis

[Sebastian P. Luque]

Hi,

After importing a grid with readGDAL(), a `SpatialGridDataFrame' object
is produced that looks correct, except the y-axis is flipped upside
down, despite the note in the "Value" section in ?readGDAL.  So I need
to flip the grid across the horizontal axis, and searching the archives
points to an old reference to elide() in maptools.  However, this
doesn't take a `SpatialGridDataFrame', so I'd appreciate any suggestions
for better alternatives.  Thanks.

Cheers,

-- 
Seb