NetworkX 2 的改变（AttributeError: 'Graph' object has no attribute 'edges_iter'）

self.edges = np.array(list(self.graph.edges_iter()))
AttributeError: 'Graph' object has no attribute 'edges_iter'

改为：

self.edges = np.array(list(self.graph.edges()))

下面是演示：

>>> D = nx.DiGraph()
>>> D.add_edges_from([(1, 2), (2, 3), (1, 3), (2, 4)])
>>> D.nodes
NodeView((1, 2, 3, 4))
>>> list(D.nodes)
[1, 2, 3, 4]
>>> D.edges
OutEdgeView([(1, 2), (1, 3), (2, 3), (2, 4)])
>>> list(D.edges)
[(1, 2), (1, 3), (2, 3), (2, 4)]
>>> D.in_degree[2]
1
>>> D.out_degree[2]
2
>>> D.in_edges
InEdgeView([(1, 2), (1, 3), (2, 3), (2, 4)])
>>> list(D.in_edges())
[(1, 2), (1, 3), (2, 3), (2, 4)]
>>> D.out_edges(2)
OutEdgeDataView([(2, 3), (2, 4)])
>>> list(D.out_edges(2))
[(2, 3), (2, 4)]
>>> D.in_degree
InDegreeView({1: 0, 2: 1, 3: 2, 4: 1})
>>> list(D.in_degree)
[(1, 0), (2, 1), (3, 2), (4, 1)]
>>> D.successors(2)
...>
>>> list(D.successors(2))
[3, 4]
>>> D.predecessors(2)
...>
>>> list(D.predecessors(2))
[1]