How to draw a weighted bidirectional graph with at least 3 edges going from one node to the central node?

Question

I would like to draw the following graph using networkx with random edge weights.

The point is that at least 3 edges have to go from nodes 2 and 3 to node 1.

I followed the code from here and got the following:

G = nx.DiGraph()
edge_list = [(1,2,{'w':'A1'}),(2,1,{'w':'A2'}), (2, 1, {'w':'A3'}), (1,3,{'w':'B'}),(3,1,{'w':'C'})]
G.add_edges_from(edge_list)
pos=nx.spring_layout(G,seed=5)
fig, ax = plt.subplots()
nx.draw_networkx_nodes(G, pos, ax=ax)
nx.draw_networkx_labels(G, pos, ax=ax)

curved_edges = [edge for edge in G.edges() if reversed(edge) in G.edges()]
straight_edges = list(set(G.edges()) - set(curved_edges))
nx.draw_networkx_edges(G, pos, ax=ax, edgelist=straight_edges)
arc_rad = 0.25
nx.draw_networkx_edges(G, pos, ax=ax, edgelist=curved_edges, connectionstyle=f'arc3, rad = {arc_rad}')

The first issue is that all the edges have to be undirected or at least bidirectional. Secondly, I added one more edge from 1 to 2 but it does not show up in the final graph.

How do I fix these two issues?

score 0 · Answer 1 · answered Mar 18 '23 at 08:08

Okay, I discovered some code that closely resembles what I require here (refer to Lee's response) and was able to modify it to meet my needs. Here's the code and the outcome.

G=nx.MultiGraph()
edge_list = [(1,2,{'w':'A1'}),(2,1,{'w':'A2'}), (2, 1, {'w':'A3'}), (1,3,{'w':'B'}),(3,1,{'w':'C'}), (3, 1, {'w':'D'})]

G.add_edges_from(edge_list)
pos = nx.random_layout(G) # pos=nx.spring_layout(G,seed=5)

nx.draw_networkx_nodes(G, pos, node_color = 'b', node_size = 500, alpha = 1)
nx.draw_networkx_labels(G, pos, font_color='w') 

ax = plt.gca()
for e in G.edges:
    ax.annotate("",
                xy=pos[e[0]], xycoords='data',
                xytext=pos[e[1]], textcoords='data',
                arrowprops=dict(arrowstyle="-", color="0.5",
                                shrinkA=5, shrinkB=5,
                                patchA=None, patchB=None,
                                connectionstyle="arc3,rad=rrr".replace('rrr',str(0.3*e[2])
                                ),
                                ),
                )
plt.axis('off')
plt.show()

To put the node in "front" (so you can't see the multiple edges pointing at the node), you need to set the shrinkA and shrinkB higher (10).

How to draw a weighted bidirectional graph with at least 3 edges going from one node to the central node?

1 Answers1