[GRASS5] Re: GRASS 5.7: Vector networking tutorial

[Greg Sepesi]

Markus Neteler wrote:
> Greg,
> 
> just FYI: The vector data are here:
> http://frida.intevation.org/
> 
> Markus

Here are the results of running dgtable (i.e., Directed Graph
implemented with lookup tables) ShortestPath variants on the FRIDA
data.  The screen dumps come from a Windows application in which I'm
using dgtable to conflate vector maps.  I'm also using dgtable in the
creation of vector maps for handhelds running Palm OS.  I believe the
last Shortest Path variant (i.e., points to graph) is equivalent to the
reportedly slow v.net.iso function.

Greg

- - -

shortest path variant: point to point
dgtable function:      FindShortestPath
example application:   driving directions
screen dump:           http://www.eduneer.com/dgtable/sp00.png
execution time:        0.16 seconds
comments:              green circle represents starting point
                       yellow path is shortest path
                       red circle represents destination

shortest path variant: point to graph
dgtable function:      FindShortestPath (with destination argument = 0)
example application:   pizza delivery range
screen dump:           http://www.eduneer.com/dgtable/sp01.png
execution time:        0.16 seconds
comments:              green circle represent starting point
                       green lines are middle third of cost range
                       yellow lines are final third of cost range
                       red lines are not reachable (as defined by the
graph)

shortest path variant: points to point
dgtable function:      FindShortestPathMultipleStartingPoints
example application:   dispatch closest police car
screen dump:           http://www.eduneer.com/dgtable/sp10.png
execution time:        0.44 seconds
comments:              green circles represent starting points
                       yellow path is shortest path
                       red circle represents destination

shortest path variant: points to graph
dgtable function:      FindShortestPathMultipleStartingPoints (with
destination argument = 0)
example application:   planning location of distribution warehouses
screen dump:           http://www.eduneer.com/dgtable/sp11.png
execution time:        0.44 seconds
comments:              green circle represents starting point
                       green lines are middle third of cost range
                       yellow lines are final third of cost range
                       red lines are not reachable (as defined by the
graph)