Balance metric that uses the Shannon-Wiener statistic of
information content. The b2 measure is given by the sum over the depths of
all tips, divided by \(2^{d}\), e.g. \(\sum d_i / 2^{d_i}\)
Usage
b2(phy, normalization = "none")
Arguments
- phy
phylo object or ltable
- normalization
"none" or "yule", when "yule" is chosen, the statistic
is divided by the Yule expectation, following from theorem 3.7 in Bienvenu
2020.
References
K.-T. Shao and R. R. Sokal. Tree Balance.
Systematic Zoology, 39(3):266, 1990. doi: 10.2307/2992186.
Bienvenu, François, Gabriel Cardona, and Celine Scornavacca.
"Revisiting Shao and Sokal’s $$ B_2 $$ B 2 index of phylogenetic balance."
Journal of Mathematical Biology 83.5 (2021): 1-43.