Module Zonal Grid Statistics
The module calculates zonal statistics and reports these in a table. The module can be used to create a contingency table of unique condition units (UCUs). These units are delineated from a zonal grid (e.g. sub catchments) and optional categorical grids (e.g. landcover, soil, ...). It is possible to calculate descriptive statistics (n, min, max, mean, standard deviation and sum) for each UCU from optional grids with continious data (e.g. slope; aspect must be handled specially, please use the "Aspect" input parameter for such a grid). The number of input grids is only limited by available memory.
The module has four different modes of operation:
(1) only a zonal grid is used as input. This results in a simple contingency table with the number of grid cells in each zone.
(2) a zonal grid and additional categorical grids are used as input. This results in a contingency table with the number of cells in each UCU.
(3) a zonal grid and additional grids with continuous data are used as input. This results in a contingency table with the number of cells in each zone and some simple statistics for each zone. The statistics are calculated for each continuous grid.
(4) a zonal grid, additional categorical grids and additional grids with continuous data are used as input. This results in a contingency table with the number of cells in each UCU and the corresponding statistics for each continuous grid.
Depending on the mode of operation, the output table contains information about the categorical combination of each UCU, the number of cells in each UCU and the statistics for each UCU. A typical output table may look like this:
| ID Zone | ID 1stCat | ID 2ndCat | Count UCU | N 1stCont | MIN 1stCont | MAX 1stCont | MEAN 1stCont | STDDEV 1stCont | SUM 1stCont |
| 0 | 2 | 6 | 6 | 6 | 708.5 | 862.0 | 734.5 | 62.5 | 4406.8 |
| 0 | 3 | 4 | 106 | 106 | 829.1 | 910.1 | 848.8 | 28.5 | 89969.0 |
- Author: Copyrights (c) 2005 by Volker Wichmann
- Specification: grid
- Menu: Spatial and Geostatistics|Grids
Parameters
| | Name | Type | Identifier | Description | Constraints |
|---|
| Input | Zone Grid | Grid (input) | ZONES | Grid defining the zones to analyse. This grid also acts as a mask. Coding: NoData / categorial values. | - |
| Categorical Grids (*) | Grid list (optional input) | CATLIST | Grids used to delineate the UCUs. Coding: NoData / categorical values. | - |
| Grids to analyse (*) | Grid list (optional input) | STATLIST | Grids with continuous data, statistics are calculated for each grid. Coding: NoData / continuous values. | - |
| Aspect (*) | Grid (optional input) | ASPECT | Aspect grid, in radians. | - |
| Output | Zonal Statistics | Table (output) | OUTTAB | Summary table. | - |
| Options | Short Field Names | Boolean | SHORTNAMES | - | Default: 1 |
| (*) optional |
Command-line
Usage: saga_cmd statistics_grid 5 [-ZONES <str>] [-CATLIST <str>] [-STATLIST <str>] [-ASPECT <str>] [-OUTTAB <str>] [-SHORTNAMES <str>]
-ZONES:<str> Zone Grid
Grid (input)
-CATLIST:<str> Categorical Grids
Grid list (optional input)
-STATLIST:<str> Grids to analyse
Grid list (optional input)
-ASPECT:<str> Aspect
Grid (optional input)
-OUTTAB:<str> Zonal Statistics
Table (output)
-SHORTNAMES:<str> Short Field Names
Boolean
Default: 1