contracted_nodes¶

contracted_nodes(G, u, v, self_loops=True)[source]¶

Returns the graph that results from contracting u and v.

Node contraction identifies the two nodes as a single node incident to any edge that was incident to the original two nodes.

Parameters:	G (NetworkX graph) – The graph whose nodes will be contracted. v (u,) – Must be nodes in G. self_loops (Boolean) – If this is True, any edges joining u and v in G become self-loops on the new node in the returned graph.
Returns:	A new graph object of the same type as G (leaving G unmodified) with u and v identified in a single node. The right node v will be merged into the node u, so only u will appear in the returned graph.
Return type:	Networkx graph

Examples

Contracting two nonadjacent nodes of the cycle graph on four nodes yields the path graph (ignoring parallel edges):

>>> import networkx as nx
>>> G = nx.cycle_graph(4)
>>> M = nx.contracted_nodes(G, 1, 3)
>>> P3 = nx.path_graph(3)
>>> nx.is_isomorphic(M, P3)
True

See also

contracted_edge(), quotient_graph()

Notes

This function is also available as identified_nodes.