ult {compositions} | R Documentation |
Compute the uncentered log ratio transform of a (dataset of) composition(s) and its inverse.
ult( x ) ult.inv( z ) Kappa( x )
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 |
The ult-transform is simply the elementwise log of the closed composition. The ult has some important properties in the scope of Information Theory.
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.
(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))