Range-apply

Apply a function to a range of the layers of a SpatRaster that varies by cell. The range is specified for each cell with one or two SpatRasters (arguments first and last). For either first or last you can use a single number instead.

You cannot use single numbers for both first and last because in that case you could use app or Summary-methods, perhaps subsetting the layers of a SpatRaster.

See selectRange to create a new SpatRaster by extracting one or more values starting at a cell-varying layer.

# S4 method for SpatRaster
rapp(x, first, last, fun, ..., allyrs=FALSE, fill=NA, 
        clamp=FALSE, circular=FALSE, 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. If TRUE, values for all layers are passed to fun but the values outside of the range are set to fill

fill

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

clamp

logical. If FALSE and the specified range is outside 1:nlyr(x) all cells are considered NA. Otherwise, the invalid part of the range is ignored

circular

logical. If TRUE the values are considered circular, such as the days of the year. In that case, if first > last the layers used are c(first:nlyr(x), 1:last). Otherwise, the range would be considered invalid and NA would be returned

filename

character. Output filename

overwrite

logical. If TRUE, filename is overwritten

wopt

list with named options for writing files as in writeRaster

Value

SpatRaster

Examples

r <- rast(ncols=9, nrows=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)))