Removing Edges from a Graph

Question

I made a graph with weights. I am trying to remove Node1's weights. I removed the Node1 but it's weights are still there. How can I remove the weights too? My code:

import networkx as nx
import matplotlib.pyplot as plt
G=nx.DiGraph()
i=1

#Adding nodes to graph
# "pos" is for the location of the nodes
G.add_node(0,pos=(0,5))
G.add_node(1,pos=(10,0))
G.add_node(2,pos=(5,-5))
G.add_node(3,pos=(-5,-5))
G.add_node(4,pos=(-10,0))

# Adding edges each node
G.add_edge(0,4,weight=2)
G.add_edge(0,1,weight=5)
G.add_edge(0,2,weight=3)


G.add_edge(1,3,weight=6)
G.add_edge(1,2,weight=2)

G.add_edge(2,1,weight=1)
G.add_edge(2,3,weight=2)

G.add_edge(4,3,weight=4)
G.add_edge(4,2,weight=10)
G.add_edge(4,1,weight=6)

pos=nx.get_node_attributes(G,'pos')
list = [nx.dijkstra_path(G,4,1,6),nx.dijkstra_path(G,4,2,10),nx.dijkstra_path(G,4,3,4)]
print((list))
print("Shortest path btwn 4-1:",nx.dijkstra_path(G,4,1),"=",nx.dijkstra_path_length(G,4,1))
print("Shortest path btwn 4-2:",nx.dijkstra_path(G,4,2),"=",nx.dijkstra_path_length(G,4,2))
print("Shortest path btwn 4-3:",nx.dijkstra_path(G,4,3),"=",nx.dijkstra_path_length(G,4,3))

labels = nx.get_edge_attributes(G,'weight', )
print("Before removing Node 1: ",G.nodes)

nx.draw_networkx_edge_labels(G,pos,edge_labels=labels, )
nx.draw(G, pos, with_labels=True)

plt.show()
plt.clf() #Clears the current figure.

G.remove_node(1) # this line of code remove only vertex, don't forget also remove weights

print("*****************")
print("******************")
print("After removing Node1: ",G.nodes)
nx.draw_networkx_edge_labels(G,pos,edge_labels=labels, )
nx.draw(G, pos, with_labels=True)
plt.show()

My figure before removing Node1:

My figure after removing Node1:

Answer 1

The reason why the edge weights are plotted is that the weights are not updated after removing a node. Hence, pos and labels in your script should be recalculated after removing the node:

G.remove_node(1) # this line of code remove only vertex, don't forget also remove weights
labels = nx.get_edge_attributes(G,'weight', )
pos=nx.get_node_attributes(G,'pos')

This is the full example:

import networkx as nx
import matplotlib.pyplot as plt
G=nx.DiGraph()
i=1

#Adding nodes to graph
# "pos" is for the location of the nodes
G.add_node(0,pos=(0,5))
G.add_node(1,pos=(10,0))
G.add_node(2,pos=(5,-5))
G.add_node(3,pos=(-5,-5))
G.add_node(4,pos=(-10,0))

# Adding edges each node
G.add_edge(0,4,weight=2)
G.add_edge(0,1,weight=5)
G.add_edge(0,2,weight=3)


G.add_edge(1,3,weight=6)
G.add_edge(1,2,weight=2)

G.add_edge(2,1,weight=1)
G.add_edge(2,3,weight=2)

G.add_edge(4,3,weight=4)
G.add_edge(4,2,weight=10)
G.add_edge(4,1,weight=6)

pos=nx.get_node_attributes(G,'pos')
list = [nx.dijkstra_path(G,4,1,6),nx.dijkstra_path(G,4,2,10),nx.dijkstra_path(G,4,3,4)]
print((list))
print("Shortest path btwn 4-1:",nx.dijkstra_path(G,4,1),"=",nx.dijkstra_path_length(G,4,1))
print("Shortest path btwn 4-2:",nx.dijkstra_path(G,4,2),"=",nx.dijkstra_path_length(G,4,2))
print("Shortest path btwn 4-3:",nx.dijkstra_path(G,4,3),"=",nx.dijkstra_path_length(G,4,3))

labels = nx.get_edge_attributes(G,'weight', )
print("Before removing Node 1: ",G.nodes)

nx.draw_networkx_edge_labels(G,pos,edge_labels=labels, )
nx.draw(G, pos, with_labels=True)

plt.show()
plt.clf() #Clears the current figure.

G.remove_node(1) # this line of code remove only vertex, don't forget also remove weights
labels = nx.get_edge_attributes(G,'weight', )
pos=nx.get_node_attributes(G,'pos')

print("*****************")
print("******************")
print("After removing Node1: ",G.nodes)
nx.draw_networkx_edge_labels(G,pos,edge_labels=labels, )
nx.draw(G, pos, with_labels=True)
plt.show()