如何在networkx图中绘制半满节点？

import networkx as nx
import matplotlib.pyplot as plt

G = nx.DiGraph()

G.add_node(1)
G.add_node(2)
G.add_edge(1, 2)

def set_node_attributes(G, node, color, size):
    nx.set_node_attributes(G, {node: {'color': color, 'size': size}})

set_node_attributes(G, 1, 'red', 200)
set_node_attributes(G, 2, 'blue', 100)

pos = nx.spring_layout(G)
nx.draw_networkx_nodes(G, pos, node_color=[G.nodes[n]['color'] for n in G.nodes()], node_size=[G.nodes[n]['size'] for n in G.nodes()])
nx.draw_networkx_edges(G, pos)
plt.axis('off')
plt.show()