This function returns the cell numbers for a Raster* object that are within a specfied extent (rectangular area), supply an object of class Extent, or another Raster* object.
Usage
cellsFromExtent(object, extent, expand=FALSE)
Arguments
object
A Raster* object
extent
An object of class Extent (which you can create with newExtent(), or another Raster* object )
expand
Logical. If TRUE, NA is returned for (virtual) cells implied by bndbox,
that are outside the RasterLayer (object). If FALSE, only cell numbers for the area where object