# Python program to create an undirected
# graph and add nodes and edges to a graph
# To import package
import networkx as nx
# To create an empty undirected graph
G = nx.Graph()
# To add a node
G.add_node(1)
G.add_node(2)
G.add_node(3)
G.add_nodes_from([4, 7, 9])
# To add an edge
# Note graph is undirected
# Hence order of nodes in edge doesn't matter
G.add_edge(1,2)
G.add_edge(3,1)
G.add_edge(2,4)
G.add_edges_from([(4, 1), (9, 1), (1, 7), (2, 9)])
# To get all the nodes of a graph
node_list = G.nodes()
print("#1")
print(node_list)
# To get all the edges of a graph
edge_list = G.edges()
print("#2")
print(edge_list)
# To remove a node of a graph
G.remove_node(3)
node_list = G.nodes()
print("#3")
print(node_list)
# To remove an edge of a graph
G.remove_edge(1,2)
edge_list = G.edges()
print("#4")
print(edge_list)
# To find number of nodes
n = G.number_of_nodes()
print("#5")
print(n)
# To find number of edges
m = G.number_of_edges()
print("#6")
print(m)
# To find degree of a node
# d will store degree of node 2
d = G.degree(2)
print("#7")
print(d)
# To find all the neighbor of a node
neighbor_list = G.neighbors(2)
print("#8")
print(neighbor_list)
#To delete all the nodes and edges
G.clear()
