How to delete all related nodes in a directed graph using networkx?

Question

I\'m not sure exactly sure what the correct terminology is for my question so I\'ll just explain what I want to do. I have a directed graph and after I delete a node I want all

Answer 1

Let me provide you with the python networkX code that solves your task:

import networkx as nx
import matplotlib.pyplot as plt#for the purpose of drawing the graphs
DG=nx.DiGraph()
DG.add_edges_from([(3,8),(3,10),(5,11),(7,11),(7,8),(11,2),(11,9),(11,10),(8,9)])
DG.remove_node(11)

connected_components method surprisingly doesn't work on the directed graphs, so we turn the graph to undirected, find out not connected nodes and then delete them from the directed graph

UG=DG.to_undirected()
not_connected_nodes=[]
for component in nx.connected_components(UG):
    if len(component)==1:#if it's not connected, there's only one node inside
        not_connected_nodes.append(component[0])
for node in not_connected_nodes:
    DG.remove_node(node)#delete non-connected nodes

If you want to see the result, add to the script the following two lines:

nx.draw(DG)
plt.show()