Multinomial function

Multinomial distribution

Multinomial distribution

Probability mass function and random generation for the multinomial distribution.

dmnom(x, size, prob, log = FALSE) rmnom(n, size, prob)

Arguments

  • x: kk-column matrix of quantiles.
  • size: numeric vector; number of trials (zero or more).
  • prob: kk-column numeric matrix; probability of success on each trial.
  • log: logical; if TRUE, probabilities p are given as log(p).
  • n: number of observations. If length(n) > 1, the length is taken to be the number required.

Details

Probability mass function

f(x)=n!i=1kxii=1kpixif(x)=n!/prod(x[i]!)prod(p[i]x[i]) f(x) = \frac{n!}{\prod_{i=1}^k x_i} \prod_{i=1}^k p_i^{x_i}f(x) = n!/prod(x[i]!) * prod(p[i]^x[i])

Examples

# Generating 10 random draws from multinomial distribution # parametrized using a vector (x <- rmnom(10, 3, c(1/3, 1/3, 1/3))) # Results are consistent with dmultinom() from stats: all.equal(dmultinom(x[1,], 3, c(1/3, 1/3, 1/3)), dmnom(x[1, , drop = FALSE], 3, c(1/3, 1/3, 1/3)))

References

Gentle, J.E. (2006). Random number generation and Monte Carlo methods. Springer.

See Also

Binomial, Multinomial

  • Maintainer: Tymoteusz Wolodzko
  • License: GPL-2
  • Last published: 2023-11-30