[GRASS-dev] v.net.alloc / v.net.iso: very long running time

[Moritz Lennert]

Hello,

I'm testing some of the vector network features and am confronted with 
an extremely long running time.

Using the North Carolina data set, I start out by adding the schools 
into the street network:

v.net input=streets_wake at PERMANENT points=schools_wake at PERMANENT 
output=streets_schools_net operation=connect alayer=1 nlayer=2 thresh=200

Then trying either

v.net.alloc input=streets_schools_net output=subnets alayer=1
nlayer=2 ccats=37,127,135,59,38-39,159

or a similar v.net.iso command, I get

Building graph...
Registering arcs...
  100%
Flattening the graph...
Graph was built
Number of centres: [7] (nlayer: [2])
Calculating costs from centres...

and then a percentage indication which stays at 0% for a very long 
time... I actually let the module run for a night and it still hadn't 
advanced much.

Cutting the network to a small region makes the programs run. So there 
seems to a severe efficiency problem in the algorithms used which grows 
very quickly with file size...


Moritz