Add a 3D plotting example with matplotlib to the gallery (#4268)

* Add a 3D drawing example using matplotlib

Based on the mayavi example, but using mpl_toolkits.mplot3d instead.

* Rename to get sphinx gallery to pick up file

* Change title.

1 files changed, 51 insertions, 0 deletions

diff --git a/examples/3d_drawing/plot_basic.py b/examples/3d_drawing/plot_basic.py
new file mode 100644
index 00000000..75a9c79a
--- /dev/null
+++ b/examples/3d_drawing/plot_basic.py
@@ -0,0 +1,51 @@
+"""
+================
+Basic matplotlib
+================
+
+A basic example of 3D Graph visualization using `mpl_toolkits.mplot_3d`.
+
+"""
+
+import networkx as nx
+import numpy as np
+import matplotlib.pyplot as plt
+from mpl_toolkits.mplot3d import Axes3D
+
+# The graph to visualize
+G = nx.cycle_graph(20)
+
+# 3d spring layout
+pos = nx.spring_layout(G, dim=3, seed=779)
+# Extract node and edge positions from the layout
+node_xyz = np.array([pos[v] for v in sorted(G)])
+edge_xyz = np.array([(pos[u], pos[v]) for u, v in G.edges()])
+
+# Create the 3D figure
+fig = plt.figure()
+ax = fig.add_subplot(111, projection="3d")
+
+# Plot the nodes - alpha is scaled by "depth" automatically
+ax.scatter(*node_xyz.T, s=100, ec="w")
+
+# Plot the edges
+for vizedge in edge_xyz:
+    ax.plot(*vizedge.T, color="tab:gray")
+
+
+def _format_axes(ax):
+    """Visualization options for the 3D axes."""
+    # Turn gridlines off
+    ax.grid(False)
+    # Suppress tick labels
+    for dim in (ax.xaxis, ax.yaxis, ax.zaxis):
+        dim.set_ticks([])
+    # Set axes labels
+    ax.set_xlabel("x")
+    ax.set_ylabel("y")
+    ax.set_zlabel("z")
+
+
+_format_axes(ax)
+fig.tight_layout()
+plt.show()