Balance metric that returns the total number of internal nodes
that are not-symmetric (confusingly enough). A node is considered symmetric
when both daughter trees have the same topology, measured as having the
same sum of depths, where depth is measured as the distance from the root
to the node/tip.
Usage
sym_nodes(phy, normalization = "none")
Arguments
- phy
phylo object or ltable
- normalization
"none" or "tips", in which case the resulting statistic
is divided by the number of tips - 2 (e.g. the maximum value of the symmetry
nodes index for a tree).
Value
Maximum depth (in number of edges)
References
S. J. Kersting and M. Fischer. Measuring tree balance using
symmetry nodes — A new balance index and its extremal properties.
Mathematical Biosciences, page 108690, 2021. ISSN 0025-5564.
doi:https://doi.org/10.1016/j.mbs.2021.108690