---
name: "r.li.cwed"
section: "1grass"
platform: "linux"
package: "grass-doc"
version: "8.4.1-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/r.li.cwed"
---

# r.li.cwed(1grass)

Calculates contrast weighted edge density index on a raster map

## NAME

**r.li.cwed**  - Calculates contrast weighted edge density index on a raster map

## KEYWORDS

raster, landscape structure analysis, patch index

## SYNOPSIS

**r.li.cwed**\
 **r.li.cwed --help**\
 **r.li.cwed** **input**=*name* **config**=*name* **path**=*name* **output**=*name*  \[--**overwrite**\]  \[--**help**\]  \[--**verbose**\]  \[--**quiet**\]  \[--**ui**\]

### Flags:

- **--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**=*name* **\[required\]**

  Name of input raster map

- **config**=*name* **\[required\]**

  Configuration file

- **path**=*name* **\[required\]**

  Name of file that contains the weight to calculate the index

- **output**=*name* **\[required\]**

  Name for output raster map

## DESCRIPTION

*r.li.cwed* (contrast weighted edge density) calculates the edge density between patch types specified:

with:

- •

  **k**: attribute

- •

  **m**: number of non-null attributes in the sampling area

- •

  **eik**: total length of edge in landscape between patch types i and k

- •

   **dik**: dissimilarity (edge contrast weight) between patch types i and k

- •

  **Area**: total landscape area

The input file contains a row for each couple of patch type that we want to consider in the calculation. Each row must be saved using this syntax:\
 patchType1,patchType2,dissimilarityBetweenPatchType1andPatchType2

## NOTES

Do not use absolute path names for the **config** and **output** file/map parameters. If the "moving window" method was selected in **g.gui.rlisetup**, then the output will be a raster map, otherwise an ASCII file will be generated in the folder `C:\Users\userxy\AppData\Roaming\GRASS8\r.li\output\` (MS-Windows) or `$HOME/.grass8/r.li/output/` (GNU/Linux).

If the sample area contains only NULL values it is considered to have 0 patch and CWED=0. If Area is 0 *r.li.cwed* returns -1. This is only possible if the map is masked.\
 If you want to change these -1 values to NULL, run subsequently on the resulting map:\

```
r.null setnull=-1 input=my_map
```

after index calculation.

## EXAMPLES

To calculate the contrast weighted edge density index on map *my\_map*, using *my\_conf* configuration file (previously defined with *g.gui.rlisetup*) and saving results in *my\_out*, run:\

```
r.li.cwed input=my_map conf=my_conf output=my_out \
          path=/path/to/weights.csv
```

Example for input "weights.csv" file:\

```
12,16,0.65
44,123,0.32
56,12,0.54
23,66,0.99
```

## SEE ALSO

*r.li - package overview,* *g.gui.rlisetup*

## REFERENCES

McGarigal, K., and B. J. Marks. 1995. FRAGSTATS: spatial pattern analysis program for quantifying landscape structure. USDA For. Serv. Gen. Tech. Rep. PNW-351. (PDF)

## AUTHORS

Serena Pallecchi, student of Computer Science University of Pisa (Italy).\
 Commission from Faunalia Pontedera (PI), Italy (www.faunalia.it)\
 Markus Metz

## SOURCE CODE

Available at: r.li.cwed source code (history)

Accessed: Monday Feb 24 17:50:42 2025

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