## NAME

r.weight2 - Weighted overlay raster map layer analysis program.
(GRASS Raster Program)

## SYNOPSIS

r.weight2 [output] [action] [color]
r.weight2 [output=option] [action=option] [color=option]

## DESCRIPTION

r.weight2 is the non-interactive version of r.weight. Both programs allow the user to assign numeric values (i.e., "weights") to individual category values within raster map layers. These weights are then distributed locationally throughout a raster map layer based on the distribution of the categories with which they are associated. The user can weight the categories of several raster map layers in a data base. Such weighted raster map layers can then be overlain. r.weight2 will combine weights in the overlain map layers by cell location.

A resulting output raster map layer depicts the combination of map layer weights across a landscape. These values represent a hierarchy of suitability for some user-defined purpose. To obtain a more detailed description, see the manual entry for r.weight .

    Output raster map must be specified	(no default)
    Action must be either (add or mult)	(default: add)
    Color table for the new raster map (grey | wave | ramp)	(default: grey)

Once the r.weight2 command line is entered, the user will need to enter a raster map layer name and assign numeric values to its categories. Values can be assigned to the categories of up to six raster map layers within r.weight2 in a single analysis. Help is available to the user by typing r.weight2 help.

## EXAMPLE

The following is the format in which data should be entered to r.weight2:

  Raster_layer1
  [Reclass rule 1a]
  [Reclass rule 1b]
  Raster_layer2
  [Reclass rule 2a]
  etc.
  end

Raster_layer: raster_map OR "raster_map in mapset" Reclass rule: (example) 1 = 5 OR 20 thru 50 = 10 (must leave spaces between the category, =, and value entries)

Example: (the prompts are shown in bold)

  > r.weight2 sites add wave
  > soils

    soils> 1 thru 20 = 5
    soils> 21 thru 30 = 10
    soils> landcover

    landcover> 1 = 2
    landcover> 2 = 4
    landcover> 3 thru 8 = 6
    landcover> end

## NOTES

The user must be knowledgeable about r.weight to run r.weight2. r.weight2 does not provide the user with a listing of raster map layers or map layer categories. Users unsure about raster map layer names should run the GRASS program g.list . To obtain a listing of the categories for a raster map layer run r.report .

The user can create an input file containing the data needed to run r.weight2. This file must list the raster map layer and reclass rules in the format shown in the above example. The prompts must not be included in the file. This file can be directed into r.weight2 at the command line by typing

  r.weight2 output action color < input_file

## BUGS

When entering data for the reclass rules, if the user does not include spaces between the category, =, and value, the program will assume that the entry is a raster map layer.

## SEE ALSO

g.list
r.combine
r.infer
r.report
r.weight

## AUTHOR

Dave Gerdes, U.S.Army Construction Engineering Research Laboratory

Last changed: $Date: 2002/01/25 05:45:34 $