writeCDF function

Write raster data to a NetCDF file

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

## 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 written 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

Returns

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)