networkx.algorithms.minors.contracted_nodes¶

contracted_nodes
(G, u, v, self_loops=True)[source]¶ Returns the graph that results from contracting
u
andv
.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.
 u, v (nodes) – Must be nodes in
G
.  self_loops (Boolean) – If this is True, any edges joining
u
andv
inG
become selfloops on the new node in the returned graph.
Returns: A new graph object of the same type as
G
(leavingG
unmodified) withu
andv
identified in a single node. The right nodev
will be merged into the nodeu
, so onlyu
will appear in the returned graph.Return type: Networkx graph
Notes
For multigraphs, the edge keys for the realigned edges may not be the same as the edge keys for the old edges. This is natural because edge keys are unique only within each pair of nodes.
Examples
Contracting two nonadjacent nodes of the cycle graph on four nodes
C_4
yields the path graph (ignoring parallel edges):>>> G = nx.cycle_graph(4) >>> M = nx.contracted_nodes(G, 1, 3) >>> P3 = nx.path_graph(3) >>> nx.is_isomorphic(M, P3) True >>> G = nx.MultiGraph(P3) >>> M = nx.contracted_nodes(G, 0, 2) >>> M.edges MultiEdgeView([(0, 1, 0), (0, 1, 1)]) >>> G = nx.Graph([(1,2), (2,2)]) >>> H = nx.contracted_nodes(G, 1, 2, self_loops=False) >>> list(H.nodes()) [1] >>> list(H.edges()) [(1, 1)]
See also
Notes
This function is also available as
identified_nodes
.