[GRASSLIST:2930] Re: shortest path

[Maliheh]

Hello Radim, 
thanks a lot for your response.

...in 'v.net.path' module. I want to know if we don't
> determine the 'afcol', 'abcol' and 'ncol' costs,
then
> what is measured for finding path? 

Length of network segments and 0 for nodes.

-- Does it mean, if we have a road network digital
map, this value is equal to length of the road 'x' for
example?

> and when we specify
> these values how they influence in algorithm?

These values are taken as costs of whole segments,
i.e.
the length of segments is not used. For example, if
you have for each
line in the network attribute 'max_speed' and
'length', you can get 
more precise results, if you are looking for fastest
path, using 
afcol=length/max_speed (pg driver)

-- And you mean that if we want to find the fastest
path on a road map, we should know the length and some
other values about each road and specify them in
attribute table for it?
Would you please tell me more, what is the name of
algorithm that GRASS uses for finding path?

Best Regards
Maliheh

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