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Note: A new GRASS GIS stable version has been released: GRASS GIS 7.4, available here.
Updated manual page: here


r.null - Manages NULL-values of given raster map.


raster, null data


r.null --help
r.null [-fincr] map=name [setnull=val[-val][,val[-val],...]] [null=float] [--help] [--verbose] [--quiet] [--ui]


Only do the work if the map is floating-point
Only do the work if the map is integer
Only do the work if the map doesn't have a NULL-value bitmap file
Create NULL-value bitmap file validating all data cells
Remove NULL-value bitmap file
Print usage summary
Verbose module output
Quiet module output
Force launching GUI dialog


map=name [required]
Name of raster map for which to edit null values
List of cell values to be set to NULL
The value to replace the null value by

Table of contents


The function of r.null is to explicitly create the NULL-value bitmap file. The intended usage is to fix "old" maps that don't have a NULL-value bitmap file (i.e. to indicate if zero is valid value or is to be converted to NULL). The module does not work with reclassified maps.

The design is flexible. Ranges of values can be set to NULL and/or the NULL value can be eliminated and replace with a specified value.

The setnull parameter is used to specify values in the ranges to be set to NULL. A range is either a single value (e.g., 5.3), or a pair of values (e.g., 4.76-34.56). Existing NULL-values are left NULL, unless the null argument is requested.

The null parameter eliminates the NULL value and replaces it with value. This argument is applied only to existing NULL values, and not to the NULLs created by the setnull argument.


Set specific values of a classified map to NULL:
r.null map=landcover.30m setnull=21,22
Set NULL-values of a map to a specific value:
r.null map=fields null=99


Note that value is restricted to integer if the map is an integer map.

r.null and reclassified maps:
The problem is, if r.null was run on the reclass raster it would alter the original and any other reclass rasters of the original. Therefore r.null doesn't allow recoding reclassified maps (products of r.reclass).
So, the way to recode such a map is: The user makes a raster out of the reclass that isn't a reclass by copying it:

r.mapcalc newmap = reclass

SEE ALSO and r.quant


U.S.Army Construction Engineering Research Laboratory

Last changed: $Date: 2015-07-11 07:04:13 -0700 (Sat, 11 Jul 2015) $


Available at: r.null source code (history)

Note: A new GRASS GIS stable version has been released: GRASS GIS 7.4, available here.
Updated manual page: here

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© 2003-2018 GRASS Development Team, GRASS GIS 7.0.7svn Reference Manual