共同的“外出”邻居和共同的“邻居”

Question

从有向图中给出两个顶点（v，u），我需要找到：Common＆＃39; out＆＃39;邻居和共同＆＃39; in＆＃39;邻居。

E.g：

import networkx as nx

ghybrid = nx.DiGraph()
ghybrid.add_edge("A", "B")
ghybrid.add_edge("A", "C")
ghybrid.add_edge("B", "D")
ghybrid.add_edge("D", "C")
ghybrid.add_edge("E", "A")
ghybrid.add_edge("E", "D")

我想要这个：

# Common out Neighbors
B ,  E :  set(['D'])
E ,  B :  set(['D'])
A ,  D :  set(['C'])
D ,  A :  set(['C'])

# Common in Neighbors
A ,  D :  set(['E'])
D ,  A :  set(['E'])

我可以拥有Common＆＃39; out＆＃39;邻居：

def common_out_neighbors(g, i, j):
    return set(g.neighbors(i)).intersection(g.neighbors(j))

但是，我不知道如何让Common＆＃39; in＆＃39; Neigbors。任何人都可以帮助我吗？

Answer 1

对于DiGraphs，您可以使用predecessors和successors方法：

import networkx as nx

def common_out_neighbors(g, i, j):
    return set(g.successors(i)).intersection(g.successors(j))

def common_in_neighbors(g, i, j):
    return set(g.predecessors(i)).intersection(g.predecessors(j))


if __name__ == '__main__':

    ghybrid = nx.DiGraph()
    ghybrid.add_edge("A", "B")
    ghybrid.add_edge("A", "C")
    ghybrid.add_edge("B", "D")
    ghybrid.add_edge("D", "C")
    ghybrid.add_edge("E", "A")
    ghybrid.add_edge("E", "D")
    print common_out_neighbors(ghybrid, 'A', 'D')
    print common_in_neighbors(ghybrid, 'A', 'D')
# output 
# set(['C'])
# set(['E'])