rapp function

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. methods

## S4 method for signature '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

Returns

SpatRaster

See Also

selectRange, app, Summary-methods, lapp, tapp

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)))