.TH r.null 1grass "" "GRASS 7.2.0" "Grass User's Manual"
.SH NAME
\fI\fBr.null\fR\fR  \- Manages NULL\-values of given raster map.
.SH KEYWORDS
raster, null data
.SH SYNOPSIS
\fBr.null\fR
.br
\fBr.null \-\-help\fR
.br
\fBr.null\fR [\-\fBfincrz\fR] \fBmap\fR=\fIname\fR  [\fBsetnull\fR=\fIval[\-val]\fR[,\fIval[\-val]\fR,...]]   [\fBnull\fR=\fIfloat\fR]   [\-\-\fBhelp\fR]  [\-\-\fBverbose\fR]  [\-\-\fBquiet\fR]  [\-\-\fBui\fR]
.SS Flags:
.IP "\fB\-f\fR" 4m
.br
Only do the work if the map is floating\-point
.IP "\fB\-i\fR" 4m
.br
Only do the work if the map is integer
.IP "\fB\-n\fR" 4m
.br
Only do the work if the map doesn\(cqt have a NULL\-value bitmap file
.IP "\fB\-c\fR" 4m
.br
Create NULL\-value bitmap file validating all data cells
.IP "\fB\-r\fR" 4m
.br
Remove NULL\-value bitmap file
.IP "\fB\-z\fR" 4m
.br
Re\-create NULL\-value bitmap file (to compress or uncompress)
.IP "\fB\-\-help\fR" 4m
.br
Print usage summary
.IP "\fB\-\-verbose\fR" 4m
.br
Verbose module output
.IP "\fB\-\-quiet\fR" 4m
.br
Quiet module output
.IP "\fB\-\-ui\fR" 4m
.br
Force launching GUI dialog
.SS Parameters:
.IP "\fBmap\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name of raster map for which to edit null values
.IP "\fBsetnull\fR=\fIval[\-val][,\fIval[\-val]\fR,...]\fR" 4m
.br
List of cell values to be set to NULL
.IP "\fBnull\fR=\fIfloat\fR" 4m
.br
The value to replace the null value by
.SH DESCRIPTION
The function of \fIr.null\fR is to explicitly create the NULL\-value
bitmap file. The intended usage is to fix \(dqold\(dq maps that don\(cqt 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.
.PP
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.
.PP
The \fBsetnull\fR 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.
.PP
The \fBnull\fR 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.
.SH EXAMPLES
Set specific values of a classified map to NULL:
.br
.br
.nf
\fC
r.null map=landcover.30m setnull=21,22
\fR
.fi
Set NULL\-values of a map to a specific value:
.br
.br
.nf
\fC
r.null map=fields null=99
\fR
.fi
.SH NOTES
Note that value is restricted to integer if the map is an integer map.
.PP
\fIr.null\fR and reclassified maps:
.br
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\(cqt allow recoding reclassified maps (products of r.reclass).
.br
So, the way to recode such a map is: The user makes a raster out of the
reclass that isn\(cqt a reclass by copying it:
.br
.br
.nf
\fC
r.mapcalc newmap = reclass
\fR
.fi
.SH SEE ALSO
\fIr.support\fR
and
\fIr.quant\fR
.SH AUTHOR
U.S.Army Construction Engineering Research Laboratory
.PP
\fILast changed: $Date: 2015\-07\-11 16:01:46 +0200 (Sat, 11 Jul 2015) $\fR
.SH SOURCE CODE
.PP
Available at: r.null source code (history)
.PP
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.PP
© 2003\-2016
GRASS Development Team,
GRASS GIS 7.2.0 Reference Manual