terra (version 0.5-2)

local: Local statistics

Description

Compute cell (pixel) level "local" statistics across layers, and most return a single layer (the exception is range).

The following summary methods are available for SpatRaster: any, all, max, min, mean, prod, range, stdev, sum

See app to compute statistics that are not included here (e.g. median) or any other custom functions.

See modal to compute the mode.

Because generic functions are used, the method applied is chosen based on the first argument: "x". This means that if r is a SpatRaster, mean(r, 5) will work, but mean(5, r) will not work.

The mean method has an argument "trim" that is ignored.

The stdev mehtod returns the population standard deviation, computed as such:

f <- function(x) sqrt(sum((x-mean(x))^2) / length(x))

This is different than the sample standard deviation retunred by sd (which uses n-1 as denominator). Function f above is equivalent to function g below

g <- function(x) sqrt(sum((x-mean(x))^2) / length(x))

Usage

# S4 method for SpatRaster
min(x, ..., na.rm=FALSE)
# S4 method for SpatRaster
max(x, ..., na.rm=FALSE)
# S4 method for SpatRaster
range(x, ..., na.rm=FALSE)
# S4 method for SpatRaster
mean(x, ..., trim=NA, na.rm=FALSE)
# S4 method for SpatRaster
stdev(x, ..., na.rm=FALSE)

Arguments

x

SpatRaster

...

additional argument of the same type as x or numeric

trim

ignored

na.rm

logical. If TRUE, NA values are ignored. If FALSE, NA is returned if x has any NA values

Value

SpatRaster

See Also

Math-methods, modal

Examples

# NOT RUN {
set.seed(0)
r <- rast(nrow=10, ncol=10, nlyr=3)
values(r) <- runif(size(r))

x <- mean(r)
x <- sum(r, r[[2]], 3)
max(r)
max(r, 0.5)

y <- stdev(r)
# not the same as 
yy <- app(r, sd)

z <- stdev(r, r*2)
# }