writeCDF: Write raster data to a NetCDF file

In terra: Spatial Data Analysis

Write raster data to a NetCDF file

Description

Write a SpatRaster or SpatRasterDataset to a NetCDF file.

When using a SpatRasterDataset, the varname, longname, and unit should be set in the object (see examples).

Always use the ".nc" or ".cdf" file extension to assure that the file can be properly read again by GDAL

Usage

## S4 method for signature 'SpatRaster'
writeCDF(x, filename, varname, longname="", unit="", split=FALSE, ...)

## S4 method for signature 'SpatRasterDataset'
writeCDF(x, filename, overwrite=FALSE, zname="time", atts="", 
    gridmap="", prec="float", compression=NA, missval, ...)

Arguments

x	SpatRaster or SpatRasterDataset
filename	character. Output filename
varname	character. Name of the dataset
longname	character. Long name of the dataset
unit	character. Unit of the data
split	logical. If TRUE each layer of x is treated as a sub-dataset
atts	character. A vector of additional global attributes to write. The must be formatted like c("x=a value", "y=abc")
gridmap	character. The crs is always writting to the file in standard formats. With this argument you can also write the format commonly used in netcdf files. Something like c("grid_mapping_name=lambert_azimuthal_equal_area", "longitude_of_projection_origin=10", "latitude_of_projection_origin=52", "false_easting=4321000", "false_northing=3210000")
overwrite	logical. If TRUE, filename is overwritten
zname	character. The name of the "time" dimension
prec	character. One of "double", "float", "integer", "short", "byte" or "char"
compression	Can be set to an integer between 1 (least compression) and 9 (most compression)
missval	numeric, the number used to indicate missing values
...	additional arguments passed on to the SpatRasterDataset method, and from there possibly to ncvar_def

Value

SpatRaster or SpatDataSet

See Also

see writeRaster for writing other file formats

Examples

f <- system.file("ex/elev.tif", package="terra")
r <- rast(f)
fname <- paste0(tempfile(), ".nc")
rr <- writeCDF(r, fname, overwrite=TRUE, varname="alt", 
      longname="elevation in m above sea level", unit="m")

a <- rast(ncols=5, nrows=5, nl=50)
values(a) <- 1:prod(dim(a))
time(a) <- as.Date("2020-12-31") + 1:nlyr(a)
aa <- writeCDF(a, fname, overwrite=TRUE, varname="power", 
      longname="my nice data", unit="U/Pa")

b <- sqrt(a)
s <- sds(a, b)
names(s) <- c("temp", "prec")
longnames(s) <- c("temperature (C)", "precipitation (mm)")
units(s) <- c("°C", "mm")
ss <- writeCDF(s, fname, overwrite=TRUE)

# for CRAN
file.remove(fname)

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