rast: Convert a GRaster to a SpatRaster

In adamlilith/fasterRaster: Faster Raster and Spatial Vector Processing Using 'GRASS GIS'

Convert a GRaster to a SpatRaster

Description

The fasterRaster version of the rast() function converts a GRaster to a SpatRaster (from the terra package).

Usage

## S4 method for signature 'GRaster'
rast(x, mm = FALSE, ...)

Arguments

x	A GRaster.
mm	Logical: If TRUE, call terra::setMinMax() on the raster to ensure it has metadata on the minimum and maximum values. For large rasters, this can take a long time, so the default value of mm is FALSE.
...	Additional arguments to send to writeRaster(). These are typically unneeded, though bigTiff may be of use if the raster is large, and supplying datatype can speed conversion of large rasters. See writeRaster().

Value

A SpatRaster (terra package).

See Also

terra::rast()

Examples

if (grassStarted()) {

# Setup
library(terra)

# Example data
madElev <- fastData("madElev")
madForest2000 <- fastData("madForest2000")

# Convert SpatRasters to GRasters
elev <- fast(madElev)
forest <- fast(madForest2000)

### GRaster properties

# plotting
plot(elev)

# dimensions
dim(elev) # rows, columns, depths, layers
nrow(elev) # rows
ncol(elev) # columns
ndepth(elev) # depths
nlyr(elev) # layers

res(elev) # resolution (2D)
res3d(elev) # resolution (3D)
zres(elev) # vertical resolution
xres(elev) # vertical resolution
yres(elev) # vertical resolution
zres(elev) # vertical resolution (NA because this is a 2D GRaster)

# cell counts
ncell(elev) # cells
ncell3d(elev) # cells (3D rasters only)

# number of NA and non-NA cells
nacell(elev)
nonnacell(elev)

# topology
topology(elev) # number of dimensions
is.2d(elev) # is it 2-dimensional?
is.3d(elev) # is it 3-dimensional?

minmax(elev) # min/max values

# "names" of the object
names(elev)

# coordinate reference system
crs(elev)
st_crs(elev)
coordRef(elev)

# extent (bounding box)
ext(elev)

# vertical extent (not defined for this raster)
zext(elev)

# data type
datatype(elev) # fasterRaster type
datatype(elev, "GRASS") # GRASS type
datatype(elev, "terra") # terra type
datatype(elev, "GDAL") # GDAL type

is.integer(elev)
is.float(elev)
is.double(elev)
is.factor(elev)

# convert data type
as.int(elev) # integer; note that "elev" is already of type "integer"
as.float(elev) # floating-precision
as.doub(elev) # double-precision

# assigning
pie <- elev
pie[] <- pi # assign all cells to the value of pi
pie

# concatenating multiple GRasters
rasts <- c(elev, forest)
rasts

# subsetting
rasts[[1]]
rasts[["madForest2000"]]

# replacing
rasts[[2]] <- 2 * forest
rasts

# adding layers
rasts[[3]] <- elev > 500 # add a layer
rasts <- c(rasts, sqrt(elev)) # add another
add(rasts) <- ln(elev)
rasts

# names
names(rasts)
names(rasts) <- c("elev_meters", "2_x_forest", "high_elevation", "sqrt_elev", "ln_elev")
rasts

# remove a layer
rasts[["2_x_forest"]] <- NULL
rasts

# number of layers
nlyr(rasts)

# correlation and covariance matrices
madLANDSAT <- fastData("madLANDSAT")
landsat <- fast(madLANDSAT) # projects matrix
layerCor(landsat) # correlation
layerCor(landsat, fun = 'cov') # covariance

}

adamlilith/fasterRaster documentation built on Dec. 21, 2024, 2:04 a.m.