| zonal {terra} | R Documentation |
Compute zonal statistics, that is summarized values of a SpatRaster for each "zone" defined by another SpatRaster.
If fun is a true function, zonal may fail for very large SpatRaster objects, except for the functions ("mean", "min", "max", or "sum").
## S4 method for signature 'SpatRaster,SpatRaster' zonal(x, z, fun=mean, ...)
x |
SpatRaster |
z |
SpatRaster with values representing zones |
fun |
function to be applied to summarize the values by zone. Either as character: "mean", "min", "max", "sum", or, for relatively small SpatRasters, a proper function |
... |
additional arguments passed to fun |
A data.frame with a value for each zone (unique value in zones)
See global for "global" statistics (i.e., all of x is considered a single zone), app for local statistics, and extract for summarizing values for polygons
r <- rast(ncols=10, nrows=10)
values(r) <- 1:ncell(r)
z <- rast(r)
values(z) <- rep(1:4, each=25)
zonal(r, z, "sum", na.rm=TRUE)
# multiple layers
r <- rast(system.file("ex/logo.tif", package = "terra"))
# zonal layer
z <- rast(r, 1)
values(z) <- rep(1:4, each=ncell(r)/4, len=ncell(r))
zonal(r, z, "mean", na.rm = TRUE)