Provided by: grass-doc_7.4.0-1_all bug


       r.cross  - Creates a cross product of the category values from multiple raster map layers.


       raster, statistics


       r.cross --help
       r.cross  [-z]  input=string[,string,...] output=name  [--overwrite]  [--help]  [--verbose]
       [--quiet]  [--ui]

           Non-zero data only

           Allow output files to overwrite existing files

           Print usage summary

           Verbose module output

           Quiet module output

           Force launching GUI dialog

       input=string[,string,...] [required]
           Names of 2-30 input raster maps

       output=name [required]
           Name for output raster map


       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.


       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

       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.


       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


       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.


       r.covar, r.stats


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

       Last changed: $Date: 2016-01-28 12:21:34 +0100 (Thu, 28 Jan 2016) $


       Available at: r.cross source code (history)

       Main index | Raster index | Topics index | Keywords index | Graphical index | Full index

       © 2003-2018 GRASS Development Team, GRASS GIS 7.4.0 Reference Manual