r.category
Manages category values and labels associated with user-specified raster map layers.
r.category map=name [cats=range [,range,...]] [values=float [,float,...]] [separator=character] [raster=name] [rules=name] [format=string] [coefficients=mult1,offset1,mult2,offset2] output_format=name [color_format=name] [--verbose] [--quiet] [--qq] [--ui]
Example:
r.category map=name output_format=plain
grass.script.run_command("r.category", map, cats=None, values=None, separator="tab", raster=None, rules=None, format=None, coefficients=None, output_format="plain", color_format="none", verbose=False, quiet=False, superquiet=False)
Example:
gs.run_command("r.category", map="name", output_format="plain")
Parameters
map=name [required]
Name of raster map
cats=range [,range,...]
Category values
Example: 1,3,7-9,13
values=float [,float,...]
Comma separated value list
Example: 1.4,3.8,13
separator=character
Field separator
Special characters: pipe, comma, space, tab, newline
Default: tab
raster=name
Raster map from which to copy category table
rules=name
File containing category label rules (or "-" to read from stdin)
format=string
Default label or format string for dynamic labeling
Used when no explicit label exists for the category
coefficients=mult1,offset1,mult2,offset2
Dynamic label coefficients
Two pairs of category multiplier and offsets, for $1 and $2
output_format=name [required]
Output format
Allowed values: plain, json
Default: plain
plain: Plain text output
json: JSON (JavaScript Object Notation)
color_format=name
Color format
Color format for output values or none.
Allowed values: none, rgb, hex, triplet, hsv
Default: none
rgb: output color in RGB format
hex: output color in HEX format
triplet: output color in colon-separated RGB format
hsv: output color in HSV format (experimental)
--help
Print usage summary
--verbose
Verbose module output
--quiet
Quiet module output
--qq
Very quiet module output
--ui
Force launching GUI dialog
map : str, required
Name of raster map
Used as: input, raster, name
cats : str | list[str], optional
Category values
Example: 1,3,7-9,13
Used as: input, cats, range
values : float | list[float] | str, optional
Comma separated value list
Example: 1.4,3.8,13
separator : str, optional
Field separator
Special characters: pipe, comma, space, tab, newline
Used as: input, separator, character
Default: tab
raster : str, optional
Raster map from which to copy category table
Used as: input, raster, name
rules : str, optional
File containing category label rules (or "-" to read from stdin)
Used as: input, file, name
format : str, optional
Default label or format string for dynamic labeling
Used when no explicit label exists for the category
coefficients : tuple[float, float, float, float] | list[float] | str, optional
Dynamic label coefficients
Two pairs of category multiplier and offsets, for $1 and $2
Used as: mult1,offset1,mult2,offset2
output_format : str, required
Output format
Used as: name
Allowed values: plain, json
plain: Plain text output
json: JSON (JavaScript Object Notation)
Default: plain
color_format : str, optional
Color format
Color format for output values or none.
Used as: name
Allowed values: none, rgb, hex, triplet, hsv
rgb: output color in RGB format
hex: output color in HEX format
triplet: output color in colon-separated RGB format
hsv: output color in HSV format (experimental)
Default: none
verbose: bool, optional
Verbose module output
Default: False
quiet: bool, optional
Quiet module output
Default: False
superquiet: bool, optional
Very quiet module output
Default: False
DESCRIPTION
r.category prints the category values and labels for the raster map layer specified by map=name to standard output. You can also use it to set category labels for a raster map.
The user can specify all needed parameters on the command line, and run the program non-interactively. If the user does not specify any categories (e.g., using the optional cats=range[,range,...] argument), then all the category values and labels for the named raster map layer that occur in the map are printed. The entire map is read using r.describe, to determine which categories occur in the map. If a listing of categories is specified, then the labels for those categories only are printed. The cats may be specified as single category values, or as ranges of values. The user may also (optionally) specify that a field separator other than a space or tab be used to separate the category value from its corresponding category label in the output, by using the separator=character|space|tab option (see example below). If no field separator is specified by the user, a tab is used to separate these fields in the output, by default.
The output is sent to standard output in the form of one category per line, with the category value first on the line, then an ASCII TAB character (or whatever single character or space is specified using the separator parameter), then the label for the category.
NOTES
Any ASCII TAB characters which may be in the label are replaced by spaces.
The output from r.category can be redirected into a file, or piped into another program.
Input from a file
The rules option allows the user to assign category labels from values found in a file (without header). The label can refer to a single category, range of categories, floating point value, or a range of floating point values. The format is given as follows (when separator is set to colon; no white space must be used after the separator):
cat:Label
val1:val2:Label
If the filename is given as "-", the category labels are read from
stdin
Default and dynamic category labels
Default and dynamic category labels can be created for categories that are not explicitly labeled. The coefficient line can be followed by explicit category labels which override the format label generation.
0:no data
2: .
5: . ## explicit category labels
7: .
explicit labels can be also of the form:
5.5:5:9 label description
or
15:30 label description
In the format line
$1
refers to the valuenum*5.0+1000
(ie, using the first 2 coefficients)$2
refers to the valuenum*5.0+1005
(ie, using the last 2 coefficients)
$1.2
will print $1
with 2 decimal places.
Also, the form $?xxx$yyy$
translates into yyy
if the category is 1,
xxx otherwise. The $yyy$
is optional. Thus
$1 meter$?s
will become:
1 meter
(for category 1)
2 meters
(for category 2), etc.
format='Elevation: $1.2 to $2.2 feet' ## Format Statement
coefficients="5.0,1000,5.0,1005" ## Coefficients
The format and coefficients above would be used to generate the following statement in creation of the format appropriate category string for category "num":
sprintf(buff,"Elevation: %.2f to %.2f feet", num*5.0+1000, num*5.0*1005)
Note: while both the format and coefficient lines must be present a blank line for the format string will effectively suppress automatic label generation.
To use a "$
" in the label without triggering the plural test, put
"$$
" in the format string.
Use 'single quotes' when using a "$
" on the command line to avoid
unwanted shell substitution.
EXAMPLES
North Carolina sample dataset:
Printing categories
r.category map=landclass96
1 developed
2 agriculture
3 herbaceous
4 shrubland
5 forest
6 water
7 sediment
prints the values and labels associated with all of the categories in the landclass96 raster map layer.
r.category map=landclass96 cats=2,5-7
2 agriculture
5 forest
6 water
7 sediment
prints only the category values and labels for landclass96 map layer
categories 2
and 5
through 7
.
r.category map=landclass96 cats=3,4 separator=comma
3,herbaceous
4,shrubland
prints the values and labels for landclass96 map layer categories 3
and 4
, but uses ",
" (instead of a tab) as the character separating
the category values from the category values in the output.
r.category map=landclass96 cats=3,4 output_format=json
generates the following JSON output:
[
{
"category": 3,
"description": "herbaceous"
},
{
"category": 4,
"description": "shrubland"
}
]
Adding categories
Example for defining new category labels, using a colon as separator:
r.category diseasemap separator=":" rules=- << EOF
1:potential absence
2:potential presence
EOF
This sets the category values 1 and 2 to respective text labels. Alternatively, the rules can be stored in an ASCII text file and loaded via the rules parameter.
SEE ALSO
UNIX Manual entries for awk and sort
d.what.rast, r.coin, r.describe, r.support
AUTHORS
Michael Shapiro, U.S. Army Construction Engineering Research
Laboratory
Hamish Bowman, University of Otago, New Zealand (label creation options)
SOURCE CODE
Available at: r.category source code
(history)
Latest change: Thursday May 08 20:58:05 2025 in commit 4144ba8