how to generate graph ?

[kimiya]

Hi,
How do I create a graph like this?

2 Nodes whose color is different, Differs from other nodes.

thanks.

[Renger]

Hi

You could start with the techniques used in the following two models from the GAMS model library:
- Triangular Graph Circle Packing (TRICP,SEQ=395)
- Traffic Equilibrium Problem (TRAFFIC,SEQ=169)
In these models graphs are defined using mappings. (see here in the documentation.

Cheers
Renger