Configuration Instance

This example shows how to use igraph’s configuration instance to set default igraph settings. This is useful for setting global settings so that they don’t need to be explicitly stated at the beginning of every igraph project you work on.

import igraph as ig
import matplotlib.pyplot as plt
import random

First we define the default plotting backend, layout, and color palette.

ig.config["plotting.backend"] = "matplotlib"
ig.config["plotting.layout"] = "fruchterman_reingold"
ig.config["plotting.palette"] = "rainbow"

The updated configuration affects only the current session. Optionally, it can be saved using ig.config.save(). By default, this function writes the configuration to ~/.igraphrc on Linux and Max OS X systems, and in %USERPROFILE%\.igraphrc on Windows systems.

The configuration only needs to be saved to .igraphrc once, and it will be automatically used in all future sessions. Whenever you use igraph and this file exists, igraph will read its content and use those options as defaults. For example, let’s create and plot a new graph to demonstrate:

random.seed(1)
g = ig.Graph.Barabasi(n=100, m=1)

We now calculate a color value between 0-200 for all nodes, for instance by computing the vertex betweenness:

betweenness = g.betweenness()
colors = [int(i * 200 / max(betweenness)) for i in betweenness]

Finally, we can plot the graph. You will notice that even though we did not create a dedicated figure and axes, matplotlib is now used by default:

ig.plot(g, vertex_color=colors, vertex_size=15, edge_width=0.3)
plt.show()