terra: rapp – R documentation

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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 another SpatRaster with two layers. For either first or last you can use a constant instead.

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

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 signature 'SpatRaster'
rapp(x, first, last, fun, ..., allyrs=FALSE, fill=NA, 
        clamp=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. 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`
`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
`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(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)))

terra

Spatial Data Analysis

v1.2-10

GPL (>= 3)

Authors

Robert J. Hijmans [cre, aut] (<https://orcid.org/0000-0001-5872-2872>), Roger Bivand [ctb] (<https://orcid.org/0000-0003-2392-6140>), Karl Forner [ctb], Jeroen Ooms [ctb] (<https://orcid.org/0000-0002-4035-0289>), Edzer Pebesma [ctb] (<https://orcid.org/0000-0001-8049-7069>)

Initial release

2021-05-12