我有一个包含自循环的NetworkX多重有向图。根据
documentation
,这是多向图的有效属性。
多向图包含有向边。允许自循环。
但是当我试图用
MG.remove_edges_from(MG.selfloop_edges())
,中生成以下警告:
---------------------------------------------------------------------------
RuntimeError Traceback (most recent call last)
<ipython-input-13-ff3391f2296f> in <module>()
1 # remove selfloop edges from the graph
----> 2 MG.remove_edges_from(MG.selfloop_edges())
~/Program_Files/miniconda3/envs/py36/lib/python3.6/site-packages/networkx/classes/multigraph.py in remove_edges_from(self, ebunch)
603 []
604 """
--> 605 for e in ebunch:
606 try:
607 self.remove_edge(*e[:3])
~/Program_Files/miniconda3/envs/py36/lib/python3.6/site-packages/networkx/classes/function.py in <genexpr>(.0)
1154 return ((n, n)
1155 for n, nbrs in G.adj.items()
-> 1156 if n in nbrs for d in nbrs[n].values())
1157 else:
1158 return ((n, n) for n, nbrs in G.adj.items() if n in nbrs)
~/Program_Files/miniconda3/envs/py36/lib/python3.6/_collections_abc.py in __iter__(self)
759
760 def __iter__(self):
--> 761 for key in self._mapping:
762 yield self._mapping[key]
763
RuntimeError: dictionary changed size during iteration
在你从MultliDiGraph中删除selfloop的过程中,我是否遗漏了什么,或者这是NetworkX的一个bug?
演示意外错误的可复制示例:
import networkx as nx
# create an empty MultiDiGraph
MG = nx.MultiDiGraph()
# add some edges to the graph
MG.add_edges_from([(1, 2), (2, 3), (3, 1), (1, 2), (2, 1), (2, 2)])
# check the edges in the graph
MG.edges()
# remove selfloop edges from the graph
MG.remove_edges_from(MG.selfloop_edges())
此方法在有向图中的工作方式与预期一致,如下所示:
# create an empty MultiDiGraph
G = nx.DiGraph()
# add some edges to the graph
G.add_edges_from([(1, 2), (2, 3), (3, 1), (1, 2), (2, 1), (2, 2)])
# check the edges in the graph
G.edges
OutEdgeView([(1, 2), (2, 3), (2, 1), (2, 2), (3, 1)])
# remove selfloop edges from the graph
G.remove_edges_from(G.selfloop_edges())
# check the edges in the graph
G.edges()
OutEdgeView([(1, 2), (2, 3), (2, 1), (3, 1)])
