Take a systematic sample from a Raster* object.
# S4 method for Raster sampleRegular(x, size, ext=NULL, cells=FALSE, xy=FALSE, asRaster=FALSE, sp=FALSE, ...)
positive integer giving the number of items to choose.
Extent. To limit regular sampling to the area within that box
logical. Also return sampled cell numbers (if asRaster=FALSE)
TRUE, coordinates of sampled cells are also returned
TRUE, a RasterLayer or RasterBrick is returned, rather than the sampled values
TRUE, a SpatialPointsDataFrame is returned
additional arguments. None implemented
A vector (single layer object), matrix (multi-layered object; or if
xy=TRUE), Raster* object (if
asRaster=TRUE), or SpatialPointsDataFrame (if