node_boundary#
- node_boundary(G, nbunch1, nbunch2=None)[source]#
Returns the node boundary of
nbunch1
.The node boundary of a set S with respect to a set T is the set of nodes v in T such that for some u in S, there is an edge joining u to v. If T is not specified, it is assumed to be the set of all nodes not in S.
- Parameters:
- GNetworkX graph
- nbunch1iterable
Iterable of nodes in the graph representing the set of nodes whose node boundary will be returned. (This is the set S from the definition above.)
- nbunch2iterable
Iterable of nodes representing the target (or “exterior”) set of nodes. (This is the set T from the definition above.) If not specified, this is assumed to be the set of all nodes in
G
not innbunch1
.
- Returns:
- set
The node boundary of
nbunch1
with respect tonbunch2
.
Notes
Any element of
nbunch
that is not in the graphG
will be ignored.nbunch1
andnbunch2
are usually meant to be disjoint, but in the interest of speed and generality, that is not required here.Examples
>>> G = nx.wheel_graph(6)
When nbunch2=None:
>>> list(nx.node_boundary(G, (3, 4))) [0, 2, 5]
When nbunch2 is given:
>>> list(nx.node_boundary(G, (3, 4), (0, 1, 5))) [0, 5]
Additional backends implement this function
graphblas : OpenMP-enabled sparse linear algebra backend.