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to_nested_tuple(T, root, canonical_form=False)

The nested tuple representation of a tree is defined recursively. The tree with one node and no edges is represented by the empty tuple, () . A tree with k subtrees is represented by a tuple of length k in which each element is the nested tuple representation of a subtree.

Notes

This function is not the inverse of from_nested_tuple ; the only guarantee is that the rooted trees are isomorphic.

Parameters

T : NetworkX graph: An undirected graph object representing a tree.
root : node: The node in T to interpret as the root of the tree.
canonical_form : bool: If True , each tuple is sorted so that the function returns a canonical form for rooted trees. This means "lighter" subtrees will appear as nested tuples before "heavier" subtrees. In this way, each isomorphic rooted tree has the same nested tuple representation.

Returns

tuple: A nested tuple representation of the tree.

Returns a nested tuple representation of the given tree.

Examples

>>> T = nx.Graph()
>>> T.add_edges_from([(0, 1), (0, 2), (0, 3)])
>>> T.add_edges_from([(1, 4), (1, 5)])
>>> T.add_edges_from([(3, 6), (3, 7)])
>>> root = 0
>>> nx.to_nested_tuple(T, root)
(((), ()), (), ((), ()))

>>> nx.to_nested_tuple(T, root, canonical_form=True)
((), ((), ()), ((), ()))

>>> T = nx.path_graph(4)
>>> root = 0
>>> nx.to_nested_tuple(T, root)
((((),),),)

See :

Back References

The following pages refer to to this document either explicitly or contain code examples using this.

networkx.algorithms.tree.coding.from_nested_tuple networkx.algorithms.tree.coding.to_prufer_sequence

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