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r.pi.graph - Graph Theory for connectivity analysis.


raster, landscape structure analysis, connectivity analysis


r.pi.graph --help
r.pi.graph [-a] input=name output=string keyval=integer distance=float neighborhood=string index=string [--overwrite] [--help] [--verbose] [--quiet] [--ui]


Set for 8 cell-neighbors. 4 cell-neighbors are default
Allow output files to overwrite existing files
Print usage summary
Verbose module output
Quiet module output
Force launching GUI dialog


input=name [required]
Name of input raster map
output=string [required]
Name of the new raster file
keyval=integer [required]
Key value
distance=float [required]
Bounding distance [0 for maximum distance]
neighborhood=string [required]
Neighborhood definition
Options: nearest_neighbor, relative_neighbor, gabriel, spanning_tree
index=string [required]
Cluster index
Options: connectance_index, gyration_radius, cohesion_index, percent_patches, percent_area, number_patches, number_links, mean_patch_size, largest_patch_size, largest_patch_diameter, graph_diameter

Table of contents


Graph Theory for connectivity analysis.




An example for the North Carolina sample dataset using class 5 (forest): Computing a graph of all patches (4 neighbourhood rule) using a maximum distance of 10 pixel, the Gabriel method and as resulting index the largest patch diameter:
r.pi.graph input=landclass96 output=landclass96_graph keyval=5 distance=10 neighborhood=gabriel index=largest_patch_diameter
the results are 2 files:
landclass96_graph: the information of the index are provided (here a range of 3-589 of patch diameter)
landclass96_graph_clusters: the generated cluster IDs are provided (here 16 clusters are identified), doing it with a distance of 5 pixel is resulting in a total of 66 clusters.


r.pi.corearea,,, r.pi.export, r.pi.graph.dec,,, r.pi.grow, r.pi.import, r.pi.index, r.pi.lm, r.pi.odc,, r.pi.rectangle, r.pi


Programming: Elshad Shirinov
Scientific concept: Dr. Martin Wegmann
Department of Remote Sensing
Remote Sensing and Biodiversity Unit
University of Wuerzburg, Germany

Port to GRASS GIS 7: Markus Metz


Available at: r.pi.graph source code (history)

Latest change: Tuesday Sep 19 09:59:22 2023 in commit: e76c325998c8cd9053ce012a5adbb79f33ab0779

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© 2003-2023 GRASS Development Team, GRASS GIS 8.3.1dev Reference Manual