alfa.tune: Fast estimation of the value of alpha

In Compositional: Compositional Data Analysis

Fast estimation of the value of \alpha

Description

Fast estimation of the value of \alpha.

Usage

alfa.tune(x, B = 1, ncores = 1)

Arguments

x	A matrix with the compositional data. No zero vaues are allowed.
B	If no (bootstrap based) confidence intervals should be returned this should be 1 and more than 1 otherwise.
ncores	If ncores is greater than 1 parallel computing is performed. It is advisable to use it if you have many observations and or many variables, otherwise it will slow down th process.

Details

This is a faster function than alfa.profile for choosing the value of \alpha.

Value

A vector with the best alpha, the maximised log-likelihood and the log-likelihood at \alpha=0, when B = 1 (no bootstrap). If B>1 a list including:

param	The best alpha and the value of the log-likelihod, along with the 95% bootstrap based confidence intervals.
message	A message with some information about the histogram.
runtime	The time (in seconds) of the process.

Author(s)

Michail Tsagris.

R implementation and documentation: Michail Tsagris [e-mail] and Giorgos Athineou <[e-mail]>.

References

Tsagris M.T., Preston S. and Wood A.T.A. (2011). A data-based power transformation for compositional data. In Proceedings of the 4th Compositional Data Analysis Workshop, Girona, Spain. https://arxiv.org/pdf/1106.1451.pdf

See Also

alfa.profile, alfa, alfainv

Examples

library(MASS)
x <- as.matrix(iris[, 1:4])
x <- x / rowSums(x)
alfa.tune(x)
alfa.profile(x)

Compositional documentation built on Oct. 9, 2024, 5:10 p.m.