rphast (version 1.0)

tm: Tree Models

Description

Make a new tree model

Usage

tm(tree, subst.mod, rate.matrix=NULL, backgd=NULL, alphabet="ACGT",
    nratecats=1, alpha=0, rate.consts=NULL, rate.weights=NULL,
    root.leaf=NULL, likelihood=NULL)

Arguments

tree

A character string representing a phylogenetic tree in newick foromat

subst.mod

A character string giving a valid substitution mod. See subst.mods.

rate.matrix

A square matrix representing the rate of substitution from one state to the next.

backgd

A numeric vector giving the equilibrium frequencies for each state.

alphabet

A character vector containing all valid states, given in the order they are represented in rate.matrix and backgd. Defaults to "ACGT"

nratecats

The number of rate categories in the model. Defaults to 1.

alpha

If nratecats > 1, weight for each category is computed using a gamma distribution with shape parameter alpha.

rate.consts

The rate for each rate category. NULL if only one category.

rate.weights

Vector of numeric of length nratecats, determining the weight of each rate category. Must sum to 1 (will be normalized otherwise). May be defined implicitly by alpha.

root.leaf

Usually NULL, but if set to the name of a leaf node in the tree, the tree will be re-rooted at this leaf node.

likelihood

an optional value giving the log likelihood of this model for some alignment.

Value

• An object of class tm representing a phylogenetic model.

Details

Tree models represent a substitution process along a phylogenetic tree. They are stored as a list, with components defined by the arguments to this function.

Examples

tree <- "((human:0.01, chimp:0.01):0.03, mouse:0.3)"
subst.mod <- "JC69"
rate.mat <- matrix(runif(16), nrow=4, ncol=4)
for (i in 1:4)
  rate.mat[i,i] <- -sum(rate.mat[i,-i])
backgd <- runif(4)
backgd <- backgd/sum(backgd)
alphabet <- "ACGT"
t <- tm(tree, subst.mod, rate.mat, backgd, alphabet)
t

nratecats <- 3
alpha <- 1.5
rate.consts <- runif(nratecats, max=3.0)
root.leaf <- "human"
t <- tm(tree, subst.mod, rate.matrix=rate.mat,
        backgd=backgd, alphabet=alphabet,
        nratecats=nratecats, alpha=alpha,
        rate.consts=rate.consts, root.leaf=root.leaf)
t