Что делает “трудно кодированный” средний?

Это должно сделать работу. Это создает источник данных columndatas с местоположениями узлов x и y и именами узлов, к которым он подключен. Источник данных columndatas используется для построения меток.

#!/usr/bin/python3
import networkx as nx
from bokeh.io import show, output_notebook
from bokeh.models import Plot, Range1d, MultiLine, Circle, HoverTool, TapTool, BoxSelectTool
from bokeh.models.graphs import from_networkx, NodesAndLinkedEdges, EdgesAndLinkedNodes
from bokeh.palettes import Spectral4
from bokeh.models import LabelSet, ColumnDataSource

G=nx.karate_club_graph()

plot = Plot(plot_width=900, plot_height=500,
            x_range=Range1d(-1.1,1.1), y_range=Range1d(-1.1,1.1))
plot.title.text = "Graph Interaction Demonstration"

plot.add_tools(HoverTool(tooltips=None), TapTool(), BoxSelectTool())

graph_renderer = from_networkx(G, nx.circular_layout, scale=1, center=(0,0))


graph_renderer.node_renderer.glyph = Circle(size=15, fill_color=Spectral4[0])
graph_renderer.node_renderer.selection_glyph = Circle(size=15, fill_color=Spectral4[2])
graph_renderer.node_renderer.hover_glyph = Circle(size=15, fill_color=Spectral4[1])
graph_renderer.node_renderer.glyph.properties_with_values()
graph_renderer.edge_renderer.glyph = MultiLine(line_color="#CCCCCC", line_alpha=0.8, line_width=5)
graph_renderer.edge_renderer.selection_glyph = MultiLine(line_color=Spectral4[2], line_width=5)
graph_renderer.edge_renderer.hover_glyph = MultiLine(line_color=Spectral4[1], line_width=5)
graph_renderer.selection_policy = NodesAndLinkedEdges()
graph_renderer.inspection_policy = EdgesAndLinkedNodes()
plot.renderers.append(graph_renderer)

clubs = nx.get_node_attributes(G, 'club')
x, y = zip(*graph_renderer.layout_provider.graph_layout.values())
data = {'x': list(x), 'y': list(y), 'connectionNames': []}
for node in clubs.keys():
    connectionStr = ''
    for edge in G.edges:
        if edge[0] == node:
            connectionStr += clubs[edge[1]] + ', '
        elif edge[1] == node:
            connectionStr += clubs[edge[0]] + ', '
    data['connectionNames'].append(connectionStr.rstrip())
source = ColumnDataSource(data)
labels = LabelSet(x='x', y='y', text='connectionNames', source=source)
plot.renderers.append(labels)

show(plot)