Cut out a geographic subset
crop.Rd
Cut out a part of a SpatRaster or SpatVector.
You can crop a SpatRaster with a SpatExtent, or with another object from which an extent can be obtained. Note that the SpatRaster returned may not have the exactly the same extent as the SpatExtent supplied because you can only select entire cells (rows and columns), and you cannot add new areas. See methods like resample
and disagg
to force SpatRasters to align and extend
to add rows and/or columns.
You can only crop rectangular areas of a SpatRaster, but see argument mask=TRUE
for setting cell values within SpatRaster to NA
; or use the mask
method after crop for additional masking options.
You can crop a SpatVector with another SpatVector. If these are not polygons, the minimum convex hull is used. Unlike with intersect
the geometries and attributes of y
are not transferred to the output. You can also crop a SpatVector with a rectangle (SpatRaster, SpatExtent).
Usage
# S4 method for class 'SpatRaster'
crop(x, y, snap="near", mask=FALSE, touches=TRUE, extend=FALSE, filename="", ...)
# S4 method for class 'SpatRasterDataset'
crop(x, y, snap="near", extend=FALSE)
# S4 method for class 'SpatRasterCollection'
crop(x, y, snap="near", extend=FALSE)
# S4 method for class 'SpatVector'
crop(x, y, ext=FALSE)
# S4 method for class 'SpatGraticule'
crop(x, y)
Arguments
- x
SpatRaster or SpatVector
- y
SpatRaster, SpatVector, SpatExtent, or any other object that has a SpatExtent (
ext
returns aSpatExtent
)- snap
character. One of "near", "in", or "out". Used to align
y
to the geometry ofx
- mask
logical. Should
y
be used to mask? Only used ify
is a SpatVector, SpatRaster or sf- touches
logical. If
TRUE
andmask=TRUE
, all cells touched by lines or polygons will be masked, not just those on the line render path, or whose center point is within the polygon- extend
logical. Should rows and/or columns be added if
y
is beyond the extent ofx
? Also seeextend
- filename
character. Output filename
- ...
additional arguments for writing files as in
writeRaster
- ext
logical. Use the extent of
y
instead ofy
. This also changes the behavior wheny
is an extent in two ways: (1) points that are on the extent boundary are removed and (2) lon/lat extents that go beyond -180 or 180 degrees longitude are wrapped around the earth to include areas at the other end of the dateline
Examples
r <- rast(xmin=0, xmax=10, ymin=0, ymax=10, nrows=25, ncols=25)
values(r) <- 1:ncell(r)
e <- ext(-5, 5, -5, 5)
rc <- crop(r, e)
# crop and mask
f <- system.file("ex/elev.tif", package="terra")
r <- rast(f)
f <- system.file("ex/lux.shp", package="terra")
v <- vect(f)
cm <- crop(r, v[9:12,], mask=TRUE)
plot(cm)
lines(v)
# crop vector
f <- system.file("ex/lux.shp", package="terra")
v <- vect(f)
e <- ext(6.15, 6.3, 49.7, 49.8)
x <- crop(v, e)
plot(x, "NAME_1")