r.distance
NAME
r.distance - Locates the closest points between objects in two raster maps. (GRASS Raster Program)
SYNOPSIS
r.distance
r.distance help
r.distance [-lq] maps=map1,map2 [fs=name]
DESCRIPTION
Locates the closest points between "objects" in two raster maps. An "object" is defined as all the grid cells that have the same category number, and closest means having the shortest "straight-line" distance.
The output is an ascii list, one line per pair of objects
cat1:cat2:distance:east1:north1:east2:north2
Explanation:
- cat1
- Category number from map1
- cat2
- Category number from map2
- distance
- The distance in meters between "cat1" and "cat2"
- east1,north1
- The coordinates of the grid cell "cat1" which is closest to "cat2"
- east2,north2
- The coordinates of the grid cell "cat2" which is closest to "cat1"
COMMAND LINE OPTIONS
Flags:
- -l
- Include category labels in the output
- -q
- Run quietly
Parameters:
- maps
- Maps for computing inter-class distances
- fs
- Output field separator
- Default is a colon (:)
NOTES
The output format lends itself to filtering. For example, to "see" lines connecting each of the category pairs in two maps, filter the output using awk and then into d.map graph:
r.distance maps=map1,map2 | \
awk -F: '{print "move",$4,$5;"draw",$6,$7}' | d.mapgraph
To create a site list of all the "map1" coordinates, filter the output into awk and then into s.in.ascii:
r.distance maps=map1,map2 | \
awk -F: '{print $4,$5}' | s.in.ascii sites=name
SEE ALSO
r.buffer, r.cost, r.drain
AUTHOR
Michael Shapiro, U.S. Army Construction Engineering Research Laboratory