Colless number

Finds the Colless number for a tree. Note that the package apTreeshape has a function colless to compute the Colless imbalance 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.

colless.phylo(tree, normalise = TRUE)

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.

normalise

option to normalise the result by dividing by the number of tip pairs. Defaults to TRUE.

Value

The Colless imbalance number of the tree.

Author

Michael Boyd mboyd855@gmail.com

Michelle Kendall michelle.louise.kendall@gmail.com

Examples

## Find the Colless imbalance of a random tree with 10 tips:
tree <- rtree(10)
plot(tree)

colless.phylo(tree)
#> [1] 0.3888889