The Box-Cox transformation applied to ratios of components {Compositional}

The Box-Cox transformation applied to ratios of components

Description

The Box-Cox transformation applied to ratios of components.

Usage

bc(x, lambda)

Arguments

x

A matrix with the compositional data. The first component must be zero values free.

lambda

The value of the power transformation, it has to be between -1 and 1. If zero values are present it has to be greater than 0. If \lambda=0 the additive log-ratio transformation (alr) is applied.

Details

The Box-Cox transformation applied to ratios of components, as described in Aitchison (1986) is applied.

Value

A matrix with the transformed data.

Author(s)

Michail Tsagris.

R implementation and documentation: Michail Tsagris [e-mail].

References

Aitchison J. (1986). The statistical analysis of compositional data. Chapman & Hall.

See Also

alr, fp, green, alfa

Examples

library(MASS)
x <- as.matrix(fgl[, 2:9])
x <- x / rowSums(x)
y1 <- bc(x, 0.2)
y2 <- bc(x, 0)
rbind( colMeans(y1), colMeans(y2) )
rowSums(y1)
rowSums(y2)