6.1. Netlist to graph (networkx)

This example demonstrate how to convert a netlist to a netowrkx graph.

By default each node is assigned weight 1 and each edge is assigned weight based on how many wires it represents. In case of bus connected single edge with weight equal to length of bus is assigned.

Graph representation

import matplotlib.pyplot as plt
import networkx as nx
import spydrnet as sdn
import spydrnet_physical as sdnphy
from networkx.drawing.nx_pydot import to_pydot

netlist = sdnphy.load_netlist_by_name('basic_hierarchy')

top: sdn.Netlist = netlist.top_instance.reference
graph = top.get_connectivity_network()
nodes = graph.nodes
graph_dot = to_pydot(graph)
graph_dot.write_svg('_nx_graph.svg')

print(" ========== Nodes ==========")
print("\n".join([f"{node:2} {nodes[node]['label']:15} {nodes[node]}"
                 for node in nodes]))
print(" ========== Edges ==========")
print("\n".join(nx.generate_edgelist(graph, data=True)))

Regenerated graph with ports splits into individual nodes

graph = top.get_connectivity_network(split_ports=True)
nodes = graph.nodes
graph_dot = to_pydot(graph)
graph_dot.write_svg('_nx_graph_split.svg')

print(" ========== Nodes ==========")
print("\n".join([f"{node:2} {nodes[node]['label']:15} {nodes[node]}"
                 for node in nodes]))
print(" ========== Edges ==========")
print("\n".join(nx.generate_edgelist(graph, data=True)))