Branch Lengths Computation
This function computes branch lengths of a tree using different methods.
compute.brlen(phy, method = "Grafen", power = 1, ...)
Grafen's (1989) computation of branch lengths: each node is given a `height', namely the number of leaves of the subtree minus one, 0 for leaves. Each height is scaled so that root height is 1, and then raised at power 'rho' (> 0). Branch lengths are then computed as the difference between height of lower node and height of upper node.
If one or several numeric values are provided as
are recycled if necessary. If a function is given instead, further
arguments are given in place of
... (they must be named, see
Zero-length branches are not treated as multichotomies, and thus may
need to be collapsed (see
An object of class
phylo with branch lengths.
Grafen, A. (1989) The phylogenetic regression. Philosophical Transactions of the Royal society of London. Series B. Biological Sciences, 326, 119--157.
data(bird.orders) plot(compute.brlen(bird.orders, 1)) plot(compute.brlen(bird.orders, runif, min = 0, max = 5)) layout(matrix(1:4, 2, 2)) plot(compute.brlen(bird.orders, power=1), main=expression(rho==1)) plot(compute.brlen(bird.orders, power=3), main=expression(rho==3)) plot(compute.brlen(bird.orders, power=0.5), main=expression(rho==0.5)) plot(compute.brlen(bird.orders, power=0.1), main=expression(rho==0.1)) layout(1)