py.show()
fixedpos = {(1): (0, 0), (6): (1, 1), (11): (1, 0), (16): (0, 1)}
pos = nx.spring_layout(G, fixed=list(fixedpos.keys()), pos=fixedpos)
nx.draw_networkx(G, pos=pos)
py.show()
Group vertices in clusters using NetworkX