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sampleRandom

Random sample

Description

Take a random sample from the cell values of a Raster* object (without replacement).

Usage

## S4 method for signature 'Raster'
sampleRandom(x, size, na.rm=TRUE, ext=NULL, 
    cells=FALSE, rowcol=FALSE, xy=FALSE, sp=FALSE, asRaster=FALSE, ...)

Arguments

x

Raster* object
size

positive integer giving the number of items to choose
na.rm

logical. If TRUE (the default), NA values are removed from random sample
ext

Extent object. To limit regular sampling to the area within the extent
cells

logical. If TRUE, sampled cell numbers are also returned
rowcol

logical. If TRUE, sampled row and column numbers are also returned
xy

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

logical. If TRUE, a SpatialPointsDataFrame is returned
asRaster

logical. If TRUE, a Raster* object is returned with random cells with values, all other cells with NA
...

Additional arguments as in writeRaster. Only relevant when asRaster=TRUE

Details

With argument na.rm=TRUE, the returned sample may be smaller than requested

Value

A vector, matrix (if cells=TRUE or x is a multi-layered object), or a SpatialPointsDataFrame (if sp=TRUE )

See Also

Examples

r <- raster(system.file("external/test.grd", package="raster"))
 sampleRandom(r, size=10)
 s <- stack(r, r)
 sampleRandom(s, size=5, cells=TRUE, sp=TRUE)
raster

Geographic Data Analysis and Modeling

v3.4-10
GPL (>= 3)
Authors
Robert J. Hijmans [cre, aut] (<https://orcid.org/0000-0001-5872-2872>), Jacob van Etten [ctb], Michael Sumner [ctb], Joe Cheng [ctb], Dan Baston [ctb], Andrew Bevan [ctb], Roger Bivand [ctb], Lorenzo Busetto [ctb], Mort Canty [ctb], Ben Fasoli [ctb], David Forrest [ctb], Aniruddha Ghosh [ctb], Duncan Golicher [ctb], Josh Gray [ctb], Jonathan A. Greenberg [ctb], Paul Hiemstra [ctb], Kassel Hingee [ctb], Institute for Mathematics Applied Geosciences [cph], Charles Karney [ctb], Matteo Mattiuzzi [ctb], Steven Mosher [ctb], Babak Naimi [ctb], Jakub Nowosad [ctb], Edzer Pebesma [ctb], Oscar Perpinan Lamigueiro [ctb], Etienne B. Racine [ctb], Barry Rowlingson [ctb], Ashton Shortridge [ctb], Bill Venables [ctb], Rafael Wueest [ctb]
Initial release
2021-05-02

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