Computes ILR transformations.
Usage
transform_ilr(object, base, ...)
# S4 method for CompositionMatrix,missing
transform_ilr(object)
# S4 method for CompositionMatrix,matrix
transform_ilr(object, base)
Arguments
- object
A
CompositionMatrix
object.- base
A
matrix
giving the base of the transformation.- ...
Currently not used.
Value
An ILR
object.
Details
The ILR transformation provides the coordinates of any composition with
respect to a given orthonormal basis. transform_ilr()
uses the orthonormal
basis (Helmert matrix) originally defined by Egozcue et al. (2003).
References
Egozcue, J. J., Pawlowsky-Glahn, V., Mateu-Figueras, G. & Barceló-Vidal, C. (2003). Isometric Logratio Transformations for Compositional Data Analysis. Mathematical Geology, 35(3), 279-300. doi:10.1023/A:1023818214614 .
Greenacre, M. J. (2019). Compositional Data Analysis in Practice. Boca Raton: CRC Press.
Greenacre, M. J. (2021). Compositional Data Analysis. Annual Review of Statistics and Its Application, 8(1): 271-299. doi:10.1146/annurev-statistics-042720-124436 .
See also
Other log-ratio transformations:
transform_alr()
,
transform_clr()
,
transform_inverse()
,
transform_lr()
,
transform_plr()
Examples
## Data from Aitchison 1986
data("hongite")
## Coerce to compositional data
coda <- as_composition(hongite)
## Pairwise log-ratio
lr <- transform_lr(coda)
## Centered log-ratio
clr <- transform_clr(coda)
## Additive log-ratio
alr <- transform_alr(coda)
## Isometric log-ratio
ilr <- transform_ilr(coda)
plr <- transform_plr(coda)
## Inverse transformation
inv_clr <- transform_inverse(clr)
all.equal(coda, inv_clr)
#> [1] TRUE
inv_alr <- transform_inverse(alr)
all.equal(coda, inv_alr)
#> [1] TRUE
inv_ilr <- transform_inverse(ilr)
all.equal(coda, inv_ilr)
#> [1] TRUE
inv_plr <- transform_inverse(plr)
all.equal(coda, inv_plr)
#> [1] TRUE