Calculates the staircase-ness measure defined in Norstrom et al., Evolutionary Bioinformatics online, 8:261 (2012) tools:::Rd_expr_doi("10.4137/EBO.S9738").
Usage
stairs(tree)
Value
Two numbers corresponding to the two staircase-ness measures for a tree. These are two related measures:
1: the proportion of subtrees that are imbalanced (i.e. subtrees where the left child has more tip descendants than the right child, or vice versa)
2: the average of all the min(l,r)/max(l,r) values of each subtree, where l and r are the number of tips in the left and right children of a subtree.
Arguments
tree
a tree of class phylo or phylo4. The tree should be binary and rooted; if not it will be coerced into a binary rooted tree using multi2di, if possible.