8.8.2. networkx.algorithms.euler.eulerian_circuit¶

networkx.algorithms.euler.eulerian_circuit(G, source=None)[source]¶

Returns an iterator over the edges of an Eulerian circuit in G.

An Eulerian circuit is a closed walk that includes each edge of a graph exactly once.

Parameters:	G : NetworkX graph A graph, either directed or undirected. source : node, optional Starting node for circuit.
Returns:	edges : iterator An iterator over edges in the Eulerian circuit.
Raises:	NetworkXError If the graph is not Eulerian.

See also

is_eulerian

Notes

This is a linear time implementation of an algorithm adapted from [R675].

For general information about Euler tours, see [R676].

References

[R675]

(1, 2) J. Edmonds, E. L. Johnson. Matching, Euler tours and the Chinese postman. Mathematical programming, Volume 5, Issue 1 (1973), 111-114.

[R676]

(1, 2) http://en.wikipedia.org/wiki/Eulerian_path

Examples

To get an Eulerian circuit in an undirected graph:

>>> G = nx.complete_graph(3)
>>> list(nx.eulerian_circuit(G))
[(0, 2), (2, 1), (1, 0)]
>>> list(nx.eulerian_circuit(G, source=1))
[(1, 2), (2, 0), (0, 1)]

To get the sequence of vertices in an Eulerian circuit:

>>> [u for u, v in nx.eulerian_circuit(G)]
[0, 2, 1]