rotate {terra}

R Documentation

Rotate data along longitude

Description

Rotate a SpatRaster that has longitude coordinates from 0 to 360, to standard coordinates between -180 and 180 degrees (or vice-versa). Longitude between 0 and 360 is frequently used in global climate models.

Rotate a SpatVector as for a SpatRaster split=TRUE, or to correct for coordinates that are connected across the date line (and end up at the "other side" of the longitude scale) are reconnected.

Usage

## S4 method for signature 'SpatRaster'
rotate(x, left=TRUE, filename="", ...)

## S4 method for signature 'SpatVector'
rotate(x, longitude=0, split=FALSE, left=TRUE, normalize=FALSE)

Arguments

x	SpatRaster or SpatVector
left	logical. If TRUE, rotate to the left, else to the right
filename	character. Output filename
...	additional arguments for writing files as in writeRaster
longitude	numeric. The longitude around which to rotate
split	logical. Should geometries be split at longitude?
normalize	logical. Should the output be normalized to longitudes between -180 and 180? See normalize.longitude

Value

SpatRaster

See Also

shift and spin

Examples

x <- rast(nrows=9, ncols=18, nl=3, xmin=0, xmax=360)
v <- rep(as.vector(t(matrix(1:ncell(x), nrow=9, ncol=18))), 3)
values(x) <- v
z <- rotate(x)

#SpatVector
p <- rbind(c(3847903, 1983584 ), c(3847903, 5801864), c(8301883, 5801864), c(8301883, 1983584 ))
p <- vect(p, "polygons", crs="+init=EPSG:3347")
d <- densify(p, 100000)
g <- project(d, "+proj=longlat")

x <- rotate(g, 50)
plot(g)
lines(x, col="red")

## rotate countries to 0-360 longitude
#w <- geodata::world(path=".")
#x <- rotate(w, long=0, split=TRUE, left=FALSE)

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