Examples

Create an empty graph structure (a "null graph") with zero nodes and zero edges.

>>> from networkx import *
>>> G=Graph()

G can be grown in several ways. By adding one node at a time:

>>> G.add_node(1)

by adding a list of nodes:

>>> G.add_nodes_from([2,3])

by using an iterator:

>>> G.add_nodes_from(xrange(100,110))

or by adding any container of nodes

>>> H=path_graph(10)
>>> G.add_nodes_from(H)

H can be another graph, or dict, or set, or even a file. Any hashable object (except None) can represent a node, e.g. a Graph, a customized node object, etc.

>>> G.add_node(H)

G can also be grown by adding one edge at a time:

>>> G.add_edge( (1,2) )

by adding a list of edges:

>>> G.add_edges_from([(1,2),(1,3)])

or by adding any ebunch of edges (see above definition of an ebunch):

>>> G.add_edges_from(H.edges())

There are no complaints when adding existing nodes or edges:

>>> G=Graph()
>>> G.add_edge([(1,2),(1,3)])

will add new nodes as required.