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.

NOTES

       When run non-interactively, r.cross will not protect existing files in the user’s  mapset.  If  the  user
       specifies an output file name that already exists in his mapset, the existing file will be overwritten by
       the new r.cross output.

SEE ALSO

       r.covar, r.stats

AUTHOR

       Michael Shapiro, U.S. Army Construction Engineering Research Laboratory

       Last changed: $Date: 2011-11-08 22:24:20 +0100 (Tue, 08 Nov 2011) $

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       © 2003-2016 GRASS Development Team, GRASS GIS 7.0.3 Reference Manual

GRASS 7.0.3                                                                                      r.cross(1grass)