robCompositions (version 1.3.2)

ilr: Isometric log-ratio transformation

Description

An isometric log-ratio transformation with a special choice of the balances according to Hron et al. (2009).

Usage

ilr(x)

Arguments

x

object of class data frame or matrix with positive entries

Value

• The ilr transformed data.

Details

This choice of the balances separates all the relative information of the part $x_1$ from the remaining parts. It is useful for estimating missing values in $x_1$ by regression of the remaining variables.

References

Egozcue J.J., V. Pawlowsky-Glahn, G. Mateu-Figueras and C. Barcel'o-Vidal (2003) Isometric logratio transformations for compositional data analysis. Mathematical Geology, 35(3) 279-300. \

Hron, K. and Templ, M. and Filzmoser, P. (2008) Imputation of missing values for compositional data using classical and robust methods Research Report SM-2008-4, Vienna University of Technology, 15 pages.

See Also

invilr

Examples

require(MASS)
Sigma <- matrix(c(5.05,4.95,4.95,5.05), ncol=2, byrow=TRUE)
z <- invilr(mvrnorm(100, mu=c(0,2), Sigma=Sigma))