Construct the transformation matrix associated with additive log-ratio (alr) coordinates.
alr_basis(dim, denominator = NULL, numerator = NULL)Number of parts. It can be a single integer, a matrix or data frame, or a character vector of part names.
Part used as denominator. By default, the last part is used.
Parts used as numerators. By default, all parts except the denominator are used, preserving their original order.
A matrix defining the alr coordinate system.
Aitchison, J. (1986). The Statistical Analysis of Compositional Data. Chapman & Hall, London.
alr_basis(5)
#> alr1 alr2 alr3 alr4
#> c1 1 0 0 0
#> c2 0 1 0 0
#> c3 0 0 1 0
#> c4 0 0 0 1
#> c5 -1 -1 -1 -1
alr_basis(5, 3)
#> alr1 alr2 alr3 alr4
#> c1 1 0 0 0
#> c2 0 1 0 0
#> c3 -1 -1 -1 -1
#> c4 0 0 1 0
#> c5 0 0 0 1
alr_basis(5, 3, c(1, 5, 2, 4))
#> alr1 alr2 alr3 alr4
#> c1 1 0 0 0
#> c2 0 0 1 0
#> c3 -1 -1 -1 -1
#> c4 0 0 0 1
#> c5 0 1 0 0