Usage
randomPoints(mask, n, p, ext=NULL, extf=1.1, excludep=TRUE, prob=FALSE,
cellnumbers=FALSE, tryf=5, warn=2)
Arguments
mask
Raster* object. If the object has cell values, cells with NA
are excluded (or the first layer of the object if there are multiple layers), unless weights=TRUE
n
integer. Number of points
p
Presence points (if provided, random points won't be in the same cells (as defined by mask)
ext
Extent object. Can be used to restrict sampling to a spatial extent extf
numeric. Multiplyer to adjust the size of extent 'ext'. The default increases of 1.1 increases the extent a little (5% at each side of the extent)
excludep
logical. If TRUE
, presence points are exluded from background
prob
logical. If TRUE
the values in mask
are interpreted as probability weights (and the values should be positive numbers (or NA)). NOTE: this currently only works for rasters of a relatively modest size (that can be loaded into RAM
cellnumbers
logical. If TRUE
, cell numbers for ]code{mask} are returned rather than coordinates
tryf
numeric > 1. Multiplyer used for initial sample size from which the requested sample size is extracted after removing NA points (outside of mask)
warn
integer. 2 or higher gives most warnings. 0 or lower gives no warnings if sample size n
is not reached