Finds the Sackin index for a tree.
Note that the package apTreeshape has a function sackin to compute the Sackin index with additional options to normalise it based on the model;
we include this simple function here for convenience within this package, and for use on objects of class phylo and phylo4.
sackin.phylo(tree, normalise = FALSE)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.
option to normalise the result, default is FALSE.
The Sackin index of the tree.
## Sackin index of a random tree with 10 tips:
sackin.phylo(rtree(10))
#> [1] 44
## normalised Sackin index:
sackin.phylo(rtree(10), normalise=TRUE)
#> [1] 0.7037037