merge: Merge SpatRasters, or merge a SpatVector with a data.frame
In terra: Spatial Data Analysis

merge

R Documentation

Merge SpatRasters, or merge a SpatVector with a data.frame

Description

Merge multiple SpatRasters to create a new SpatRaster with a larger spatial extent. The SpatRasters must have the same origin and spatial resolution. In areas where the SpatRasters overlap, the values of the SpatRaster that is first in the sequence of arguments (or in the SpatRasterCollection) will be retained (unless first=FALSE). Cells that are NA are ignored unless na.rm=FALSE

There is also a method for merging SpatVector with a data.frame; that is, to join the data.frame to the attribute table of the SpatVector.

Usage

## S4 method for signature 'SpatRaster,SpatRaster'
merge(x, y, ..., first=TRUE, na.rm=TRUE, filename="", overwrite=FALSE, wopt=list())

## S4 method for signature 'SpatRasterCollection,missing'
merge(x, first=TRUE, na.rm=TRUE, filename="", ...)

## S4 method for signature 'SpatVector,data.frame'
merge(x, y, ...)

Arguments

`x`	SpatRaster, SpatRasterCollection, or SpatVector
`y`	missing if `x` is a SpatRasterCollection. SpatRaster if `x` is a SpatRaster. data.frame if `x` is a SpatVector
`...`	if `x` is a SpatRaster: additional objects of the same class as `x`. If `x` is a SpatRasterCollection: options for writing files as in `writeRaster`. If `x` is a SpatVector, the same arguments as in `merge`
`first`	logical. If `TRUE`, in areas where rasters overlap, the first value is used. Otherwise the last value is used
`na.rm`	logical. If `TRUE` values that are `NA` are 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 or SpatVector

Examples

x <- rast(xmin=-110, xmax=-80, ymin=40, ymax=70, res=1, vals=1)
y <- rast(xmin=-85, xmax=-55, ymax=60, ymin=30, res=1, vals=2)
z <- rast(xmin=-60, xmax=-30, ymax=50, ymin=20, res=1, vals=3)

m1 <- merge(x, y, z)
m2 <- merge(z, y, x)
m3 <- merge(y, x, z)

# if you have many SpatRasters, it may be convenient
# to make a SpatRasterCollection
rlist <- list(x, y, z)
rsrc <- sprc(rlist)

m <- merge(rsrc)


## SpatVector with data.frame
f <- system.file("ex/lux.shp", package="terra")
p <- vect(f)
dfr <- data.frame(District=p$NAME_1, Canton=p$NAME_2, Value=round(runif(length(p), 100, 1000)))
dfr <- dfr[1:5, ]
pm <- merge(p, dfr, all.x=TRUE, by.x=c('NAME_1', 'NAME_2'), by.y=c('District', 'Canton'))
pm
values(pm)

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