compositions (version 1.01-1)

rDirichlet: Dirichlet distribution

Description

The Dirichlet distribution on the simplex.

Usage

rDirichlet.acomp(n,alpha)
rDirichlet.rcomp(n,alpha)

Arguments

n

number of datasets to be simulated

alpha

parameters of the Dirichlet distribution

Value

• a generated random dataset of class "acomp" or "rcomp", drawn from a Dirichlet distribution with the given parameter alpha. The names of alpha are used to name the parts.

Details

The Dirichlet distribution is the result of closing a vector of equally-scaled Gamma-distributed variables. It the conjugate prior distribution for a vector of probabilities of a multinomial distribution. Thus, it generalizes the beta distribution for more than two parts.

References

Aitchison, J. (1986) The Statistical Analysis of Compositional Data Monographs on Statistics and Applied Probability. Chapman & Hall Ltd., London (UK). 416p. Mateu-Figueras, G.; Pawlowsky-Glahn, V. (2005). The Dirichlet distribution with respect to the Aitchison measure on the simplex, a first approach. In: Mateu-Figueras, G. and Barcel'o-Vidal, C. (Eds.) Proceedings of the 2nd International Workshop on Compositional Data Analysis, Universitat de Girona, ISBN 84-8458-222-1, http://ima.udg.es/Activitats/CoDaWork05

See Also

rnorm.acomp

Examples

tmp <- rDirichlet.acomp(10,alpha=c(A=2,B=0.2,C=0.2))
plot(tmp)