请注意，如果一个图可以在欧氏平面上画出而没有任何边相交，则该图是平面的。
在您的例子中，您的图形是平面的，因为交换节点1和4足以避免边相交。
然而，如果你考虑一个完全图（一个完全图Kn只有n ≤ 4是平面的），你可以看到差异。

>>> K4 = nx.complete_graph(4)
>>> nx.check_planarity(K4)
(True, <networkx.algorithms.planarity.PlanarEmbedding object at 0x1035df1d0>)
>>> K5 = nx.complete_graph(5)
>>> nx.check_planarity(K5)
(False, None)

您可以使用check_planarity的答案来绘制可能的平面布局。

import networkx as nx
import matplotlib.pyplot as plt

pos = {1: (0, 0), 2: (0, 1), 3: (1, 1), 4: (1, 0)}
G = nx.Graph().to_undirected()
G.add_nodes_from(pos)
G.add_edge(1, 3, weight=1)
G.add_edge(2, 4, weight=1)
G.add_edge(2, 3, weight=1)

is_planar, G2 = nx.check_planarity(G, False)
print(is_planar)

# plotting

fig = plt.figure()
ax = fig.add_subplot(121)
ax = plt.gca()
ax.margins(0.20)

# draws the graph as you have drawn it

nx.draw_networkx(G, with_labels=True, pos=pos)

ax = fig.add_subplot(122)
ax = plt.gca()
ax.margins(0.20)

# draws the graph without intersections => graph is planar because 
# it is possible to draw it without edge intersections

nx.draw_networkx(G2, with_labels=True)

plt.show()