Mixtures of Von Mises-Fisher distributions

Description

It performs model based clustering for circualr, spherical and hyperspherical data assuming von Mises-Fisher distributions.

Usage

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mix.vmf(x, g)

Arguments

x

A matrix with the data expressed as unit vectors.

g

The number of groups to fit. It must be greater than or equal to 2.

Details

The initial step of the algorithm is not based on a spherical k-means, but on s imple k-means. The results are comparable to the package movMF.

Value

A list including:

param

A matrix with the mean direction, the concetrations parameter and mixing probability of each group.

loglik

The value of the maximised log-likelihood.

pred

The predicted group of each observation.

runtime

The run time of the algorithm. A numeric vector. The first element is the user time, the second element is the system time and the third element is the elapsed time.

Author(s)

Michail Tsagris

R implementation and documentation: Michail Tsagris <mtsagris@yahoo.gr> and Giorgos Athineou <athineou@csd.uoc.gr>

References

Kurt Hornik and Bettina Grun (2014). movMF: An R Package for Fitting Mixtures of von Mises-Fisher Distributions http://cran.r-project.org/web/packages/movMF/vignettes/movMF.pdf

See Also

rmixvmf, bic.mixvmf, mixvmf.contour

Examples

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k <- runif(4, 4, 20)
prob <- c(0.2, 0.4, 0.3, 0.1)
mu <- matrix(rnorm(16), ncol = 4)
mu <- mu / sqrt( rowSums(mu^2) )
x <- rmixvmf(200, prob, mu, k)$x
mix.vmf(x, 3)
mix.vmf(x, 4)
mix.vmf(x, 5)

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