[GRASS-user] Unique IDs for network segments

Johannes Radinger johannesradinger at gmail.com
Wed Dec 2 06:40:39 PST 2015

Hi all,

I built a GRASS7 network using v.net:

First, I used the 'connect' option to snap some points to my network (using
the -s flag)
Second, I used that first network and also added all nodes with the 'nodes'
option to get a final network.

With the 'report' option of v.net I can report all edges with their start
and end end points. However, these edges of the final network are based on
the initial category values of the input vector. How can I get the network
split into single lines with unique IDs between each node of the final
network. In other words I want a report of v.net that contains only unique
edge categories? I'd like to write the output of v.net into a new table and
assign lengths to each edge.

For example, at the moment, a line with cat=300 is confined by a start node
cat=1 and an end node cat=2. For that case v.net reports:
300 1 2

If I connect a new node with cat=3 along that line and calculate v.net, it
300 1 3
300 3 2

Any ideas/suggestions? Maybe I need to 'break' the network lines at each
node before running v.net?

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