Subdivide a raster or polygons

Divide a SpatRaster into n parts with approximately the same sum of weights (cell values).

Divides a SpatVector of polygons into n compact and approximately equal area parts. The results are not deterministic so you should use set.seed to be able to reproduce your results. If you get a warning about non-convergence, you can increase the number of iterations used with additional argument iter.max

Usage

# S4 method for class 'SpatRaster'
divide(x, n=2, start="ns", as.raster=FALSE, na.rm=TRUE)

# S4 method for class 'SpatVector'
divide(x, n=5, w=NULL, alpha=1, ...)

Arguments

x

SpatRaster or SpatVector of polygons

n

numeric. Can be a single positive integer to indicate the number of parts (SpatVector) or the number of splits (SpatRaster).

If x is a SpatRaster, it can also be a vector with values -2, -1, 1, or 2. Where 1 means one split and 2 means two splits, and the negative sign indicates an East-West (vertical) split as opposed to a North-South split.

If x is a SpatVector it can be a list with at least one of these elements: horizontal and vertical that specify the proportions of the area that splits should cover. This can either be a single fraction such as 1/3, or a sequence of fractions in ascending order such as c(1/4, 1/2, 1)

start

character. To indicate the initial direction of splitting the raster. "ns" for North-South (horizontal) or "ew" for East-West (vertical)

as.raster

logical. If FALSE a SpatVector is returned. If FALSE, a SpatRaster is returned. If NA a list with a SpatRaster and a SpatVector is returned

na.rm

logical. If TRUE cells in x that are NA are not included in the output

w

SpatRaster with, for example, environmental data

alpha

numeric. One or two numbers that act as weights for the x and y coordinates

...

additional arguments such as iter.max passed on to kmeans

See also

thresh

Value

SpatVector or SpatRaster, or a list with both

Examples

f <- system.file("ex/elev.tif", package="terra")
r <- rast(f)
x <- divide(r, 3)
# plot(r); lines(x)


f <- system.file("ex/lux.shp", package="terra")
v <- vect(f)
d <- divide(v, 3)
dv <- divide(v, list(h=.5))