blum {treestats} | R Documentation |
The Blum index of imbalance (also known as the s-shape
statistic) calculates the sum of log(N-1)
over all internal nodes,
where N represents the total number of extant tips connected to that node.
An alternative implementation can be found in the Castor R package.
blum(phy, normalization = FALSE)
phy |
phylogeny or ltable |
normalization |
because the Blum index sums over all nodes, the resulting statistic tends to be correlated with the number of extant tips. Normalization can be performed by dividing by the number of extant tips. |
Blum index of imbalance
M. G. B. Blum and O. Francois (2006). Which random processes describe the Tree of Life? A large-scale study of phylogenetic tree imbalance. Systematic Biology. 55:685-691.
simulated_tree <- ape::rphylo(n = 10, birth = 1, death = 0)
balanced_tree <- treestats::create_fully_balanced_tree(simulated_tree)
unbalanced_tree <- treestats::create_fully_unbalanced_tree(simulated_tree)
blum(balanced_tree)
blum(unbalanced_tree) # should be higher