center#

center(G, e=None, usebounds=False, weight=None)[source]#

Returns the center of the graph G.

The center is the set of nodes with eccentricity equal to radius.

Parameters:

GNetworkX graph

A graph

eeccentricity dictionary, optional

A precomputed dictionary of eccentricities.

useboundsbool, optional

If True, use extrema bounding (see Notes) when computing the center for undirected graphs. Extrema bounding may accelerate the distance calculation for some graphs. usebounds is ignored if G is directed or if e is not None. Default is False.

weightstring, function, or None

If this is a string, then edge weights will be accessed via the edge attribute with this key (that is, the weight of the edge joining u to v will be G.edges[u, v][weight]). If no such edge attribute exists, the weight of the edge is assumed to be one.

If this is a function, the weight of an edge is the value returned by the function. The function must accept exactly three positional arguments: the two endpoints of an edge and the dictionary of edge attributes for that edge. The function must return a number.

If this is None, every edge has weight/distance/cost 1.

Weights stored as floating point values can lead to small round-off errors in distances. Use integer weights to avoid this.

Weights should be positive, since they are distances.

Returns:

clist

List of nodes in center

See also

barycenter

periphery

Notes

When usebounds=True, the computation makes use of smart lower and upper bounds and is often linear in the number of nodes, rather than quadratic (except for some border cases such as complete graphs or circle shaped-graphs).

Examples

>>> G = nx.Graph([(1, 2), (1, 3), (1, 4), (3, 4), (3, 5), (4, 5)])
>>> list(nx.center(G))
[1, 3, 4]