addLRinv {robCompositions}

Inverse additive logratio mapping

Description

Inverse additive logratio mapping, often called additive logistic transformation.

Usage

addLRinv(x, cnames = NULL, ivar = NULL, useClassInfo = TRUE)

Arguments

x

data set, object of class “alr”, “matrix” or “data.frame”

cnames

column names. If the object is of class “alr” the column names are chosen from therein.

ivar

index of the rationing part. If the object is of class “alr” the column names are chosen from therein. If not and ivar is not provided by the user, it is assumed that the rationing part was the last column of the data in the simplex.

useClassInfo

if FALSE, the class information of object x is not used.

Details

The function allows also to preserve absolute values when class info is provided. Otherwise only the relative information is preserved.

Value

the resulting compositional data matrix

Author(s)

Matthias Templ

References

Aitchison, J. (1986) The Statistical Analysis of Compositional Data Monographs on Statistics and Applied Probability. Chapman and Hall Ltd., London (UK). 416p.

See Also

pivotCoordInv, cenLRinv, cenLR, addLR

Examples

data(arcticLake)
x <- arcticLake
x.alr <- addLR(x, 2)
y <- addLRinv(x.alr)
## This exactly fulfills:
addLRinv(addLR(x, 3))
data(expenditures)
x <- expenditures
y <- addLRinv(addLR(x, 5, 2))
head(x)
head(y)
## --> absolute values are preserved as well.

## preserve only the ratios:
addLRinv(x.alr, ivar=2, useClassInfo=FALSE)