title: Networkx graph is not planar
body: <p>I am trying to draw a network graph. My code is very simple. For small case studies, this code works well. But for a larger sample with more vertices and arcs, I get G is not planar error. What is the reason for this error?</p>
  <blockquote>
  <p>D:\Anaconda3\lib\site-packages\networkx\drawing\layout.py in
  planar_layout(G, scale, center, dim)
  945         is_planar, embedding = nx.check_planarity(G)
  946         if not is_planar:
  --&gt; 947             raise nx.NetworkXException(&quot;G is not planar.&quot;)
  948     pos = nx.combinatorial_embedding_to_pos(embedding)
  949     node_list = list(embedding)</p>
  </blockquote>
  <p>NetworkXException: G is not planar.</p>
  <pre><code>def createAttackGraphNonPlanar(pos):
      G=nx.DiGraph(directed=True)
      G.add_nodes_from([nodes_map[n] for n in nodes])
      print(G.nodes())
      
      
      G.add_edges_from([  (nodes_map[e[0]],nodes_map[e[1]]) for e in arcs])
   
      nx.draw_planar(G, pos=pos, node_size=30, node_color='red', with_labels = True)
  </code></pre>