R: Functions for the Dirichlet Distribution

rdirichlet {gtools} | R Documentation

## Functions for the Dirichlet Distribution

### Description

Functions to compute the density of or generate random deviates from the Dirichlet distribution.

### Usage

    rdirichlet(n, alpha)
    ddirichlet(x, alpha)

### Arguments

`x` | A vector containing a single random deviate or matrix containing one random deviate per row.
`n` | Number of random vectors to generate.
`alpha` | Vector or (for `ddirichlet`) matrix containing shape parameters.

### Details

The Dirichlet distribution is the multidimensional generalization of the beta distribution. It is the canonical Bayesian distribution for the parameter estimates of a multinomial distribution.

### Value

`ddirichlet` returns a vector containing the Dirichlet density for the corresponding rows of `x`.

`rdirichlet` returns a matrix with `n` rows, each containing a single Dirichlet random deviate.

### Author(s)

Code original posted by Ben Bolker to R-News on Fri Dec 15 2000. See https://stat.ethz.ch/pipermail/r-help/2000-December/009561.html. Ben attributed the code to Ian Wilson i.wilson@maths.abdn.ac.uk. Subsequent modifications by Gregory R. Warnes greg@warnes.net.

### See Also

`dbeta`, `rbeta`

### Examples

      x <- rdirichlet(20, c(1,1,1) )

      ddirichlet(x, c(1,1,1) )

[Package gtools version 3.8.2 Index]