sbp_basis {coda.base}

Isometric log-ratio basis based on Balances

Description

Build an ilr_basis using a sequential binary partition or a generic coordinate system based on balances.

Usage

sbp_basis(sbp, data = NULL, fill = FALSE, silent = FALSE)

Arguments

sbp

parts to consider in the numerator and the denominator. Can be defined either using a list of formulas setting parts (see examples) or using a matrix where each column define a balance. Positive values are parts in the numerator, negative values are parts in the denominator, zeros are parts not used to build the balance.

data

composition from where name parts are extracted

fill

should the balances be completed to become an orthonormal basis? if the given balances are not orthonormal, the function will complete the balance to become a basis.

silent

inform about orthogonality

Value

matrix

Examples

X = data.frame(a=1:2, b=2:3, c=4:5, d=5:6, e=10:11, f=100:101, g=1:2)
sbp_basis(list(b1 = a~b+c+d+e+f+g,
               b2 = b~c+d+e+f+g,
               b3 = c~d+e+f+g,
               b4 = d~e+f+g,
               b5 = e~f+g,
               b6 = f~g), data = X)
sbp_basis(list(b1 = a~b,
               b2 = b1~c,
               b3 = b2~d,
               b4 = b3~e,
               b5 = b4~f,
               b6 = b5~g), data = X)
# A non-orthogonal basis can also be calculated.
sbp_basis(list(b1 = a+b+c~e+f+g,
              b2 = d~a+b+c,
              b3 = d~e+g,
              b4 = a~e+b,
              b5 = b~f,
              b6 = c~g), data = X)