Quick Start

For the eager folks out there, this intro will give you a quick overview of the following operations:

• Construct a graph

• Set attributes of nodes and edges

• Plot a graph using matplotlib

• Save the plot as an image

• Export and import a graph as a .gml file

To find out more features that igraph has to offer, check out the gallery!

/build/python-igraph-CFtWeI/python-igraph-1.0.0+ds/debian/python3-igraph/usr/lib/python3.13/dist-packages/igraph/io/files.py:494: RuntimeWarning: The boolean edge attribute 'married' was converted to numeric. Location: src/io/gml.c:1252
  return writer(f, *args, **kwds)

import igraph as ig
import matplotlib.pyplot as plt

# Construct a graph with 5 vertices
n_vertices = 5
edges = [(0, 1), (0, 2), (0, 3), (0, 4), (1, 2), (1, 3), (1, 4), (3, 4)]
g = ig.Graph(n_vertices, edges)

# Set attributes for the graph, nodes, and edges
g["title"] = "Small Social Network"
g.vs["name"] = [
    "Daniel Morillas",
    "Kathy Archer",
    "Kyle Ding",
    "Joshua Walton",
    "Jana Hoyer",
]
g.vs["gender"] = ["M", "F", "F", "M", "F"]
g.es["married"] = [False, False, False, False, False, False, False, True]

# Set individual attributes
g.vs[1]["name"] = "Kathy Morillas"
g.es[0]["married"] = True

# Plot in matplotlib
# Note that attributes can be set globally (e.g. vertex_size), or set individually using arrays (e.g. vertex_color)
fig, ax = plt.subplots(figsize=(5, 5))
ig.plot(
    g,
    target=ax,
    layout="circle",  # print nodes in a circular layout
    vertex_size=30,
    vertex_color=[
        "steelblue" if gender == "M" else "salmon" for gender in g.vs["gender"]
    ],
    vertex_frame_width=4.0,
    vertex_frame_color="white",
    vertex_label=g.vs["name"],
    vertex_label_size=7.0,
    edge_width=[2 if married else 1 for married in g.es["married"]],
    edge_color=["#7142cf" if married else "#AAA" for married in g.es["married"]],
)

plt.show()

# Save the graph as an image file
fig.savefig("social_network.png")
fig.savefig("social_network.jpg")
fig.savefig("social_network.pdf")

# Export and import a graph as a GML file.
g.save("social_network.gml")
g = ig.load("social_network.gml")