[GRASS-user] Extract subnet from grass vector network based on selected nodes

[Moritz Lennert]

On 27/09/17 21:03, Markus Metz wrote:
> 
> 
> On Wed, Sep 27, 2017 at 4:07 PM, Moritz Lennert 
> <mlennert at club.worldonline.be <mailto:mlennert at club.worldonline.be>> wrote:
>  >
>  >
>  >
>  > Le 27 septembre 2017 13:11:54 GMT+02:00, Johannes Radinger 
> <johannesradinger at gmail.com <mailto:johannesradinger at gmail.com>> a écrit :
>  > >Hi,
>  > >
>  > >I have a GRASS vector network that represents a river network (with
>  > >many
>  > >first order tributaries) and that has additional connected nodes that
>  > >represent sampling sites.
>  > >
>  > >I'd like to extract a minimum subnetwork of the full network that still
>  > >connects a set of selected nodes (e.g. identified by their cat).
>  > >However,
>  > >network edges (i.e. river segments) that are not necessary to connect
>  > >the
>  > >sampling points should be excluded in the new subnetwork. Is there a
>  > >function or process in GRASS GIS to extract such a subnetwork that
>  > >fully
>  > >connects a set of selected nodes?
>  >
>  > not sure but maybe v.net.spanningtree ?
> 
> v.net.spanningtree calculates a tree covering all nodes in the network, 
> not only selected nodes, therefore v.net.spanningtree does not apply here.

If you connect only the selected nodes to the network, wouldn't that 
work ? Or does v.net.spanningtree consider all connections between lines 
as nodes ?

Moritz