ult {compositions} | R Documentation |
Compute the uncentered log ratio transform of a (dataset of) composition(s) and its inverse.
ult( x ,...) ultInv( z ,...) Kappa( x ,...)
x |
a composition or a data matrix of compositions, not necessarily closed |
z |
the ult-transform of a composition or clr-transforms of compositions (or a data matrix), not necessarily centered |
... |
for generic use only |
The ult-transform is simply the elementwise log of the closed composition. The ult has some important properties in the scope of Information Theory of probability vectors (but might be mostly misleading for exploratory analysis of compositions).
ult
gives the uncentered log transform,
ultInv
gives closed compositions with the given
ult/clr-transforms
Kappa
gives the difference between the clr and the ult
transforms. It is quite linked to information measures.
K.Gerald v.d. Boogaart http://www.stat.boogaart.de
(tmp <- ult(c(1,2,3))) ultInv(tmp) ultInv(tmp) - clo(c(1,2,3)) # 0 data(Hydrochem) cdata <- Hydrochem[,6:19] pairs(ult(cdata),pch=".") Kappa(c(1,2,3))