[R-sig-Geo] extracting raster data with point and polygons

[Oscar Perpiñan]

Hi,
> Could you clarify
> where you would use mask() to make this more efficient for larger rasters?
> It seems this will always use all the cellnumbers. I though maybe
> mask(zones,obs) but then zonal() threw an error.

I mean that you may save computation time if you apply `cv` (or
whatever function) only over those cells that correspond to the point
observations. However, this does not work with `zonal` as you point.

Best,

Oscar.