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())





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


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


function to be applied


additional arguments passed to fun


logical. If TRUE, values for all layers are passed to fun but the values outside of the range are set to fill


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


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


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


character. Output filename


logical. If TRUE, filename is overwritten


list with named options for writing files as in writeRaster




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)))