Provided by: grass-doc_7.4.0-1_all 
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-zero 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 combinations of category values in the
raster input layers (input=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 zero data values are not crossed. This means that if a zero category value occurs in
any input data layer, the combination is assigned to category zero in the resulting map layer, even if
other data layers contain non-zero data. In the example given above, 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 not all category values are zero
will be assigned a unique category value in the resulting map layer.
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
___________
0 1
0 2
1 1
1 2
2 4
r.cross would produce a new raster map layer with 5 categories:
map1 map2 output
____________________
0 1 1
0 2 2
1 1 3
1 2 4
2 4 5
Note: The actual category value assigned to a particular combination in the result map layer is dependent
on the order in which the combinations occur in the input map layer data and can be considered
essentially 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
______________________________
1 layer1(0) layer2(1)
2 layer1(0) layer2(2)
3 layer1(1) layer2(1)
4 layer1(1) layer2(2)
5 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
Last changed: $Date: 2016-01-28 12:21:34 +0100 (Thu, 28 Jan 2016) $
SOURCE CODE
Available at: r.cross source code (history)
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