Add edge-weights to plot output in networkx

Question

I am doing some graph theory in python using the networkx package. I would like to add the weights of the edges of my graph to the plot output. How can I do this?

For example How would I modify the following code to get the desired output?

import networkx as nx
import matplotlib.pyplot as plt

G=nx.Graph()
i=1
G.add_node(i,pos=(i,i))
G.add_node(2,pos=(2,2))
G.add_node(3,pos=(1,0))
G.add_edge(1,2,weight=0.5)
G.add_edge(1,3,weight=9.8)
pos=nx.get_node_attributes(G,'pos')
nx.draw(G,pos)
plt.savefig("path.png")

I would like 0.5 and 9.8 to appear on the edges to which they refer in the graph.

JohanC · Accepted Answer · 2020-12-01 18:02:51Z

81

You'll have to call nx.draw_networkx_edge_labels(), which will allow you to... draw networkX edge labels :)

EDIT: full modified source

#!/usr/bin/python
import networkx as nx
import matplotlib.pyplot as plt

G=nx.Graph()
i=1
G.add_node(i,pos=(i,i))
G.add_node(2,pos=(2,2))
G.add_node(3,pos=(1,0))
G.add_edge(1,2,weight=0.5)
G.add_edge(1,3,weight=9.8)
pos=nx.get_node_attributes(G,'pos')
nx.draw(G,pos)
labels = nx.get_edge_attributes(G,'weight')
nx.draw_networkx_edge_labels(G,pos,edge_labels=labels)
plt.savefig(<wherever>)

edited Dec 1, 2020 at 18:02

JohanC

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answered Feb 6, 2015 at 18:19

Marcus Müller

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8 Comments

Kevin Over a year ago

This shows: {weight: xxxxx} in the edge. Anyway we can get just the number in the edge label?

Marcus Müller Over a year ago

yes. Replace labels with the number you mean. seriously, this is Python – can't be that hard to fix that line of code :)

GoingMyWay Over a year ago

It seems that nx.draw_networkx_edge_labels() can't show distance given labels, edges with larger weights shown in the plot should look longer than those with smaller weights.

Marcus Müller Over a year ago

Please ask a new question instead of raising questions in the comments. Thank you!

Nischaya Sharma Over a year ago

The link in the answer to the docs gives Error 404: Page not found so here is the new link: networkx.github.io/documentation/networkx-1.10/reference/…

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willcrack · Accepted Answer · 2020-11-26 14:44:32Z

45

I like to do it like this:

import matplotlib.pyplot as plt
pos=nx.spring_layout(G) # pos = nx.nx_agraph.graphviz_layout(G)
nx.draw_networkx(G,pos)
labels = nx.get_edge_attributes(G,'weight')
nx.draw_networkx_edge_labels(G,pos,edge_labels=labels)

edited Nov 26, 2020 at 14:44

willcrack

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answered Mar 27, 2020 at 0:35

Julio Batista Silva

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