networkx.generators.classic.empty_graph¶

empty_graph
(n=0, create_using=None, default=<class 'networkx.classes.graph.Graph'>)[source]¶ Returns the empty graph with n nodes and zero edges.
 Parameters
n (int or iterable container of nodes (default = 0)) – If n is an integer, nodes are from
range(n)
. If n is a container of nodes, those nodes appear in the graph.create_using (Graph Instance, Constructor or None) – Indicator of type of graph to return. If a Graphtype instance, then clear and use it. If None, use the
default
constructor. If a constructor, call it to create an empty graph.default (Graph constructor (optional, default = nx.Graph)) – The constructor to use if create_using is None. If None, then nx.Graph is used. This is used when passing an unknown
create_using
value through your homegrown function toempty_graph
and you want a default constructor other than nx.Graph.
Examples
>>> G = nx.empty_graph(10) >>> G.number_of_nodes() 10 >>> G.number_of_edges() 0 >>> G = nx.empty_graph("ABC") >>> G.number_of_nodes() 3 >>> sorted(G) ['A', 'B', 'C']
Notes
The variable create_using should be a Graph Constructor or a “graph”like object. Constructors, e.g.
nx.Graph
ornx.MultiGraph
will be used to create the returned graph. “graph”like objects will be cleared (nodes and edges will be removed) and refitted as an empty “graph” with nodes specified in n. This capability is useful for specifying the classnature of the resulting empty “graph” (i.e. Graph, DiGraph, MyWeirdGraphClass, etc.).The variable create_using has three main uses: Firstly, the variable create_using can be used to create an empty digraph, multigraph, etc. For example,
>>> n = 10 >>> G = nx.empty_graph(n, create_using=nx.DiGraph)
will create an empty digraph on n nodes.
Secondly, one can pass an existing graph (digraph, multigraph, etc.) via create_using. For example, if G is an existing graph (resp. digraph, multigraph, etc.), then empty_graph(n, create_using=G) will empty G (i.e. delete all nodes and edges using G.clear()) and then add n nodes and zero edges, and return the modified graph.
Thirdly, when constructing your homegrown graph creation function you can use empty_graph to construct the graph by passing a user defined create_using to empty_graph. In this case, if you want the default constructor to be other than nx.Graph, specify
default
.>>> def mygraph(n, create_using=None): ... G = nx.empty_graph(n, create_using, nx.MultiGraph) ... G.add_edges_from([(0, 1), (0, 1)]) ... return G >>> G = mygraph(3) >>> G.is_multigraph() True >>> G = mygraph(3, nx.Graph) >>> G.is_multigraph() False
See also create_empty_copy(G).