cdt {compositions} | R Documentation |
Compute the centered default transform of a (dataset of) composition or amount.
cdt(x) ## Default S3 method: cdt( x ) ## S3 method for class 'acomp': cdt( x ) ## S3 method for class 'rcomp': cdt( x ) ## S3 method for class 'aplus': cdt( x ) ## S3 method for class 'rplus': cdt( x ) ## S3 method for class 'rmult': cdt( x ) ## S3 method for class 'factor': cdt( x )
x |
a classed amount or composition (or a matrix of), to be transformed with its centered default transform |
The general idea of this package is to analyse the same data with
different geometric concepts as similar as possible. For each of the
four concepts there exists a unique transform expressing the geometry
in a linear subspace, keeping the relation to the variables. This
unique transformation is computed by cdt
. For
acomp
the transform is clr
, for
rcomp
it is cpt
, for
aplus
it is ilt
, and for
rplus
it is iit
. Each component of the result
is identified with a unit vector in the direction of the corresponding
component of the original composition or amount. Keep in mind that the
transform is not necessarily surjective and thus variances in the
image space might be singular.
A corresponding matrix or vector containing the transforms.
## Not run: # the cdt is defined by cdt <- function(x) UseMethod("cdt",x) cdt.default <- function(x) x cdt.acomp <- clr cdt.rcomp <- cpt cdt.aplus <- ilt cdt.rplus <- iit ## End(Not run) cdt(acomp(1:5)) cdt(rcomp(1:5))