compositions (version 0.9-11)

ilrBase: The canonical basis in the clr plane used for ilr and ipt transforms.

Description

Compute the basis of a clr-plane, to use with isometric log-ratio or planar transform of a (dataset of) compositions.

Usage

ilrBase( x=NULL , z=NULL , D = NULL )
          gsi.ilrBase(D)

Arguments

x

optional dataset or vector of compositions

z

optional dataset or vector containing ilr or ipt coordinates

D

number of parts of the simplex

Value

• Both methods give a matrix containing by columns the basis elements for the canonical basis of the clr-plane used for the ilr and ipt transform.

Details

ilrBase is a wrapper catching the answers of gsi.ilrBase and is to be used as the more convenient function. Only one of the arguments is needs to determine the dimension of the simplex.

References

Egozcue J.J., V. Pawlowsky-Glahn, G. Mateu-Figueras and C. Barcel'o-Vidal (2003) Isometric logratio transformations for compositional data analysis. Mathematical Geology, 35(3) 279-300

See Also

clr,ilr,ipt, http://ima.udg.es/Activitats/CoDaWork03

Examples

ilr(c(1,2,3))
ilrBase(D=2)
ilrBase(c(1,2,3))
ilrBase(z= ilr(c(1,2,3)) )
round(ilrBase(D=7),digits= 3)