# compute.brlen

From ape v2.7-3
0th

Percentile

##### Branch Lengths Computation

This function computes branch lengths of a tree using different methods.

Keywords
manip
##### Usage
compute.brlen(phy, method = "Grafen", power = 1, ...)
##### Details

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 method, they are recycled if necessary. If a function is given instead, further arguments are given in place of ... (they must be named, see examples).

Zero-length branches are not treated as multichotomies, and thus may need to be collapsed (see di2multi).

##### Value

An object of class phylo with branch lengths.

##### References

Grafen, A. (1989) The phylogenetic regression. Philosophical Transactions of the Royal society of London. Series B. Biological Sciences, 326, 119--157.

read.tree for a description of phylo objects, di2multi, multi2di

##### Examples
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)`
Documentation reproduced from package ape, version 2.7-3, License: GPL (>= 2)

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