writeRaster: Write raster data to a file

In terra: Spatial Data Analysis

Write raster data to a file

Description

Write a SpatRaster object to a file.

Usage

## S4 method for signature 'SpatRaster,character'
writeRaster(x, filename, overwrite=FALSE, ...)

Arguments

x	SpatRaster
filename	character. Output filename. Can be a single filename, or as many filenames as nlyr(x) to write a file for each layer
overwrite	logical. If TRUE, filename is overwritten
...	additional arguments for for writing files. See Details

Details

In writeRaster, and in other methods that generate SpatRaster objects, options for writing raster files to disk can be provided as additional arguments or, in a few cases, as the wopt argument (a named list) if the additional arguments are already used for a different purpose. See terraOptions to get or set default values. The following options are available:

name	description
datatype	values accepted are "INT1U", "INT2U", "INT2S", "INT4U", "INT4S", "FLT4S", "FLT8S". With GDAL >= 3.5 you can also use "INT8U" and "INT8S". And with GDAL >= 3.7 you can use also use "INT1S". See gdal to discover the GDAL version you are using. The first three letters indicate whether the datatype is an integer (whole numbers) of a real number ("float", decimal numbers), the fourth character indicates the number of bytes used for each number. Higher values allow for storing larger numbers and/or more precision; but create larger files. The "S" or "U" indicate whether the values are signed (both negative and positive) or unsigned (zero and positive values only).
filetype	file format expresses as GDAL driver names. If this argument is not supplied, the driver is derived from the filename. You can use gdal(drivers=TRUE) to see what drivers are available in your installation
gdal	GDAL driver specific datasource creation options. See the GDAL documentation. For example, with the GeoTiff file format you can use gdal=c("COMPRESS=DEFLATE", "TFW=YES").
tempdir	the path where temporary files are to be written to.
progress	positive integer. If the number of chunks is larger, a progress bar is shown.
memfrac	numeric between 0 and 0.9 (higher values give a warning). The fraction of available RAM that terra is allowed to use.
memmax	memmax - the maximum amount of RAM (in GB) that terra can use when processing a raster dataset. Should be less than what is detected (see mem_info, and higher values are ignored. Set it to a negative number or NA to ignore this value).
names	output layer names.
NAflag	numeric. value to represent missing (NA or NaN) values. See note
scale	numeric. Cell values written to disk are divided by this value (default is 1). See scoff
offset	numeric. Value that is subtracted from the cell values written to disk (default is 0). See scoff
verbose	logical. If TRUE debugging information is printed
steps	positive integers. In how many steps (chunks) do you want to process the data (for debugging)
todisk	logical. If TRUE processing operates as if the dataset is very large and needs to be written to a temporary file (for debugging).

Value

SpatRaster. This function is used for the side-effect of writing values to a file.

Note

GeoTiff files are, by default, written with LZW compression. If you do not want compression, use gdal="COMPRESS=NONE".

When writing integer values the lowest available value (given the datatype) is used to represent NA for signed types, and the highest value is used for unsigned values. This can be a problem with byte data (between 0 and 255) as the value 255 is reserved for NA. To keep the value 255, you need to set another value as NAflag, or do not set a NAflag (with NAflag=NA)

See Also

see writeCDF for writing NetCDF files.

Examples

r <- rast(nrows=5, ncols=5, vals=1:25)

# create a temporary filename for the example
f <- file.path(tempdir(), "test.tif")

writeRaster(r, f, overwrite=TRUE)

writeRaster(r, f, overwrite=TRUE, gdal=c("COMPRESS=NONE", "TFW=YES"), datatype='INT1U')

## Or with a wopt argument:

writeRaster(r, f, overwrite=TRUE, wopt= list(gdal=c("COMPRESS=NONE"), datatype='INT1U'))

## remove the file
unlink(f)

terra documentation built on Oct. 13, 2023, 5:08 p.m.