label_out_component

graph_tool.topology.label_out_component(g, root, label=None)

Label the out-component (or simply the component for undirected graphs) of a root vertex.

Parameters:

gGraph

Graph to be used.

rootVertex

The root vertex.

labelVertexPropertyMap (optional, default: None)

If provided, this must be an initialized Boolean vertex property map where the out-component will be labeled.

Returns:

labelVertexPropertyMap

Boolean vertex property map which labels the out-component.

Notes

The algorithm runs in \(O(V + E)\) time.

Examples

>>> g = gt.random_graph(100, lambda: poisson(2.2), directed=False)
>>> l = gt.label_out_component(g, g.vertex(2))
>>> print(l.a)
[1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 1 1 0 0 1 0 1 0
 1 1 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1 1 0 0 1 1 1 1 1 1 1
 1 1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 0 1 1 1 0]

The in-component can be obtained by reversing the graph.

>>> l = gt.label_out_component(gt.GraphView(g, reversed=True, directed=True),
...                            g.vertex(1))
>>> print(l.a)
[0 1 1 0 0 1 0 0 0 1 1 0 1 0 0 0 0 1 1 1 0 0 0 1 1 0 0 0 1 1 0 0 0 0 0 1 0
 1 1 0 0 0 1 1 1 1 0 1 1 1 1 1 0 0 0 1 0 0 0 0 0 0 1 1 0 0 0 0 1 0 1 0 0 0
 0 1 0 1 0 1 0 0 1 0 1 1 1 1 0 1 0 0 0 1 0 0 1 0 0 0]