Greenacre's power transformation {Compositional}

Greenacre's power transformation

Description

Greenacre's power transformation.

Usage

green(x, theta)

Arguments

x

A matrix with the compositional data.

theta

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 \theta=0 the log transformation is applied.

Details

Greenacre's transformation is applied to the compositional data.

Value

A matrix with the power transformed data.

Author(s)

Michail Tsagris.

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

References

Greenacre, M. (2009). Power transformations in correspondence analysis. Computational Statistics & Data Analysis, 53(8): 3107-3116. http://www.econ.upf.edu/~michael/work/PowerCA.pdf

See Also

alfa

Examples

library(MASS)
x <- as.matrix(fgl[, 2:9])
x <- x / rowSums(x)
y1 <- green(x, 0.1)
y2 <- green(x, 0.2)
rbind( colMeans(y1), colMeans(y2) )