ilr {robCompositions} | R Documentation |
An isometric log-ratio transformation with a special choice of the balances according to Hron et al. (2010).
ilr(x)
x |
object of class data.frame or matrix with positive entries |
The ilr transformation moves D-part compositional data from the simplex into a (D-1)-dimensional real space isometrically. From this choice of the balances, all the relative information of the part x_1 from the remaining parts is separated. It is useful for estimating missing values in x_1 by regression of the remaining variables.
The ilr transformed data.
Karel Hron, Matthias Templ
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. (2010) Imputation of missing values for compositional data using classical and robust methods Computational Statistics and Data Analysis, In Press, Corrected Proof, ISSN: 0167-9473, DOI:10.1016/j.csda.2009.11.023
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))