ult {compositions}R Documentation

Uncentered log transform

Description

Compute the uncentered log ratio transform of a (dataset of) composition(s) and its inverse.

Usage

          ult( x )
          ult.inv( z )
          Kappa( x )
          

Arguments

x a composition or a data matrix of compositions, not necessarily closed
z the ult-transform of a composition or a data matrix of clr-transforms of compositions, not necessarily centered

Details

The ult-transform is simply the elementwise log of the closed composition. The ult has some important properties in the scope of Information Theory.

Value

ult gives the uncentered log transform,
ult.inv gives closed compositions with the given ult-transforms
Kappa gives the difference between the clr and the ult transform. It is quite linked to information measures.

See Also

ilr,alr,apt

Examples

(tmp <- ult(c(1,2,3)))
ult.inv(tmp)
ult.inv(tmp) - clo(c(1,2,3)) # 0
data(Hydrochem)
cdata <- Hydrochem[,6:19]
pairs(ult(cdata))
Kappa(c(1,2,3))

[Package compositions version 0.9-10 Index]