rapp: Range-apply
In terra: Spatial Data Analysis

rapp	R Documentation

Range-apply

Description

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.

Usage

## 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`

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)))

terra documentation built on Oct. 14, 2024, 5:07 p.m.