r.cross(1grass) GRASS GIS User's Manual r.cross(1grass)
NAME
r.cross - Creates a cross product of the category values from multiple
raster map layers.
KEYWORDS
raster, statistics
SYNOPSIS
r.cross
r.cross --help
r.cross [-z] input=string[,string,...] output=name [--overwrite]
[--help] [--verbose] [--quiet] [--ui]
Flags:
-z
Non-NULL data only
--overwrite
Allow output files to overwrite existing files
--help
Print usage summary
--verbose
Verbose module output
--quiet
Quiet module output
--ui
Force launching GUI dialog
Parameters:
input=string[,string,...] [required]
Names of 2-30 input raster maps
output=name [required]
Name for output raster map
DESCRIPTION
r.cross creates an output raster map layer representing all unique com-
binations of category values in the raster input layers (in-
put=name,name,name, ...). At least two, but not more than ten, input
map layers must be specified. The user must also specify a name to be
assigned to the output raster map layer created by r.cross.
OPTIONS
The program will be run non-interactively if the user specifies the
names of between 2-10 raster map layers be used as input, and the name
of a raster map layer to hold program output.
With the -z flag NULL values are not crossed. This means that if a
NULL value occurs in any input data layer, this combination is ignored,
even if other data layers contain non-NULL data. In the example given
below, use of the -z option would cause 3 categories to be generated
instead of 5.
If the -z flag is not specified, then map layer combinations in which
some values are NULL will be assigned a unique category value in the
resulting output map.
Category values in the new output map layer will be the cross-product
of the category values from these existing input map layers.
EXAMPLE
For example, suppose that, using two raster map layers, the following
combinations occur:
map1 map2
___________
NULL 1
NULL 2
1 1
1 2
2 4
r.cross would produce a new raster map layer with 5 categories:
map1 map2 output
____________________
NULL 1 0
NULL 2 1
1 1 2
1 2 3
2 4 4
Note: The actual category value assigned to a particular combination in
the result map layer is dependent on the order in which the combina-
tions occur in the input map layer data and can be considered essen-
tially random. The example given here is illustrative only.
SUPPORT FILES
The category file created for the output raster map layer describes the
combinations of input map layer category values which generated each
category. In the above example, the category labels would be:
category category
value label
______________________________
0 layer1(0) layer2(1)
1 layer1(0) layer2(2)
2 layer1(1) layer2(1)
3 layer1(1) layer2(2)
4 layer1(2) layer2(4)
A random color table is also generated for the output map layer.
SEE ALSO
r.covar, r.stats
AUTHOR
Michael Shapiro, U.S. Army Construction Engineering Research Laboratory
SOURCE CODE
Available at: r.cross source code (history)
Accessed: unknown
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GRASS 7.8.7 r.cross(1grass)
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