direct_orthogonal: Direct Orthogonalization

In ChristianGoueguel/specProc: Preprocessing Tools For Laser-Induced Breakdown Spectroscopy (LIBS) Spectra

Direct Orthogonalization

Description

This function implements the Direct Orthogonalization (DO) algorithm, as proposed by Andersson (1999), to filter out variation from predictor variables, \textbf{X}, that is orthogonal to the response variable(s), \textbf{Y}.

Usage

direct_orthogonal(
  x,
  y,
  ncomp = 2,
  center = TRUE,
  scale = FALSE,
  max_iter = 10,
  tol = 0.001
)

Arguments

x	A matrix or data frame of the predictor variables
y	A vector, matrix or data frame of the response variable(s)
ncomp	An integer specifying the number of principal components to retain for orthogonal processing. Default is 2.
center	A logical value specifying whether to center the data. Default is TRUE.
scale	A logical value specifying whether to scale the data. Default is FALSE.
max_iter	An integer representing the maximum number of iterations. The default value is 10.
tol	A numeric value representing the tolerance for convergence. The default value is 1e-3.

Details

Contrary to the Orthogonal Signal Correction (OSC) algorithm, Wold et al. (1998), which uses inverse Partial Least Squares (PLS) regression to filter out the orthogonal signal, DO filters out the orthogonal signal directly by orthogonalization of the \textbf{X} matrix. Principal Components Analysis (PCA) is performed on the orthogonalized \textbf{X} to obtain the scores \textbf{T} and loadings \textbf{P} matrices. Direct Orthogonalization is typically simpler and faster than OSC.

Value

A list with the following components:

• correction: The corrected matrix.

• loading: The loadings matrix.

• score: The scores matrix.

Author(s)

Christian L. Goueguel

References

• Andersson, C.A., (1999). Direct orthogonalization. Chemometrics Intell. Lab. Syst., 47(1):51-63

• Pierna, J.A.F., Massart, D.L., de Noord, O.E., Ricoux, P., (2001). Direct orthogonalization: some case studies. Chemometrics Intell. Lab. Syst., 55(1-2):101-108

• Wold, S., Antti, H., Lindgren, F., Ohman, J. (1998). Orthogonal signal correction of near-infrared spectra. Chemometrics Intell. Lab. Syst., 44(1):175-185.

ChristianGoueguel/specProc documentation built on Nov. 9, 2024, 3:23 p.m.