raster (version 3.1-5)

sampleRegular: Regular sample

Description

Take a systematic sample from a Raster* object.

Usage

# S4 method for Raster
sampleRegular(x, size, ext=NULL, cells=FALSE, xy=FALSE, asRaster=FALSE, 
            sp=FALSE, useGDAL=FALSE, ...)

Arguments

x

Raster object

size

positive integer giving the number of items to choose.

ext

Extent. To limit regular sampling to the area within that box

cells

logical. Also return sampled cell numbers (if asRaster=FALSE)

xy

logical. If TRUE, coordinates of sampled cells are also returned

asRaster

logical. If TRUE, a RasterLayer or RasterBrick is returned, rather than the sampled values

sp

logical. If TRUE, a SpatialPointsDataFrame is returned

useGDAL

logical. If TRUE, GDAL is used to sample in some cases. This is quicker, but can result in values for a different set of cells than when useGDAL=FALSE. Only for rasters that are accessed via rgdal, and are not rotated. When TRUE arguments cells, xy, and sp are ignored (i.e., FALSE

...

additional arguments. None implemented

Value

A vector (single layer object), matrix (multi-layered object; or if cells=TRUE, or xy=TRUE), Raster* object (if asRaster=TRUE), or SpatialPointsDataFrame (if sp=TRUE)

See Also

sampleRandom, sampleStratified

Examples

# NOT RUN {
 r <- raster(system.file("external/test.grd", package="raster"))
 v <- sampleRegular(r, size=100)
 x <- sampleRegular(r, size=100, asRaster=TRUE)
# }