Fixed database typo and removed unnecessary class identifier.

venv/share/doc/networkx-2.5/examples/3d_drawing/README.txt

@@ -0,0 +1,2 @@
+3D Drawing
+----------

venv/share/doc/networkx-2.5/examples/3d_drawing/mayavi2_spring.py

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+"""
+=======
+Mayavi2
+=======
+
+"""
+
+import networkx as nx
+import numpy as np
+from mayavi import mlab
+
+# some graphs to try
+# H=nx.krackhardt_kite_graph()
+# H=nx.Graph();H.add_edge('a','b');H.add_edge('a','c');H.add_edge('a','d')
+# H=nx.grid_2d_graph(4,5)
+H = nx.cycle_graph(20)
+
+# reorder nodes from 0,len(G)-1
+G = nx.convert_node_labels_to_integers(H)
+# 3d spring layout
+pos = nx.spring_layout(G, dim=3)
+# numpy array of x,y,z positions in sorted node order
+xyz = np.array([pos[v] for v in sorted(G)])
+# scalar colors
+scalars = np.array(list(G.nodes())) + 5
+
+pts = mlab.points3d(
+    xyz[:, 0],
+    xyz[:, 1],
+    xyz[:, 2],
+    scalars,
+    scale_factor=0.1,
+    scale_mode="none",
+    colormap="Blues",
+    resolution=20,
+)
+
+pts.mlab_source.dataset.lines = np.array(list(G.edges()))
+tube = mlab.pipeline.tube(pts, tube_radius=0.01)
+mlab.pipeline.surface(tube, color=(0.8, 0.8, 0.8))
+mlab.show()