phylox.cherrypicking.tree_child_sequences.find_tree_child_sequence

phylox.cherrypicking.tree_child_sequences.find_tree_child_sequence(network, labels=False)

Find a tree child sequence for a network. If the network is orchard but not tree-child, this function may produce a cherry-picking sequence that reduces the network to a single edge, but that is not a tree-child sequence.

Parameters:

• network (phylox.DiNetwork) – The network to find a tree child sequence for.

• labels (bool) – Whether to return the tree child sequence as a list of labels instead of a list of nodes.

Returns:

The tree child sequence.

Return type:

list

Example:

>>> from phylox import DiNetwork
>>> N = DiNetwork(
...     edges=[(-1, 0), (0, 1), (0, 2), (1, 3), (1, 4), (2, 3), (2, 4), (3, 5), (4, 6)],
...     labels=[(5, "A"), (6, "B")],
... )
>>> try:
...     find_tree_child_sequence(N, labels=True)
... except ValueError:
...     exception_raised = True
>>> exception_raised
True

>>> N = DiNetwork(
...     edges=[(-1, 0), (0, 1), (0, 2), (1, 2), (1, 3), (2, 4), (3, 4), (3, 5), (4, 6)],
...     labels=[(5, "A"), (6, "B")],
... )
>>> TC_sequence = find_tree_child_sequence(N, labels=True)
>>> TC_sequence == [("B", "A"), ("B", "A"), ("B", "A")] or TC_sequence == [("A", "B"), ("B", "A"), ("B", "A")]
True