alr {chemometrics} | R Documentation

## additive logratio transformation

### Description

A data transformation according to the additive logratio transformation is done.

### Usage

    alr(X, divisorvar)

### Arguments

`X` | numeric data frame or matrix
`divisorvar` | number of the column of X for the variable to divide with

### Details

The alr transformation is one possibility to transform compositional data to a real space. Afterwards, the transformed data can be analyzed in the usual way.

### Value

Returns the transformed data matrix with one variable (divisor variable) less.

### Author(s)

Peter Filzmoser <P.Filzmoser@tuwien.ac.at>

### References

K. Varmuza and P. Filzmoser: Introduction to Multivariate Statistical Analysis in Chemometrics. CRC Press, Boca Raton, FL, 2009.

### See Also

`clr`,`ilr`

### Examples

    data(glass)
    glass_alr <- alr(glass,1)

[Package chemometrics version 0.6 Index]