terra (version 1.1-17)

rapp: Range-Apply

Description

Apply a function to a cell-varying range of the layers of a SpatRaster. The range is specified for each cell separately by two other SpatRasters (arguments first and last. For either first or last you can use a constant instead.

If the specified range is outside 1:nlyr(x), NA is returned. You could use clamp to assure that this is the case.

See app or Summary-methods if you want to apply a function to all layers (perhaps after making a subset) of a SpatRaster.

Usage

# S4 method for SpatRaster
rapp(x, first, last, fun, ..., allyrs=FALSE, fill=NA, 
          filename="", overwrite=FALSE, wopt=list())

Arguments

x

SpatRaster

first

SpatRaster or positive integer between 1 and nlyr(x), indicating the first layer in the range of layers to be considered

last

SpatRaster or positive integer between 1 and nlyr(x), indicating the last layer in the range to be considered

fun

function to be applied

...

additional arguments passed to fun

allyrs

logical. Should the values of all layers be passed to fun. The values outside of the range are set to fill

fill

numeric. The fill value for the the values outside of the range, for when allyrs=TRUE

filename

character. Output filename

overwrite

logical. If TRUE, filename is overwritten

wopt

list with named options for writing files as in writeRaster

Value

SpatRaster

See Also

app, Summary-methods, lapp, tapp

Examples

# NOT RUN {
r <- rast(ncol=9, nrow=9)
values(r) <- 1:ncell(r)
s <- c(r, r, r, r, r, r)
s <- s * 1:6
s[1:2] <- NA
start <- end <- rast(r)
start[] <- 1:3
end[]   <- 4:6
a <- rapp(s, start, end, fun="mean")
b <- rapp(s, start, 2, fun="mean")

# cumsum from start to nlyr(x). return all layers
r <- rapp(s, start, nlyr(s), cumsum, allyrs=TRUE, fill=0)
# return only the final value
rr <- rapp(s, start, nlyr(s), function(i) max(cumsum(i)))
# }