proximetricsR (version 0.6.5)

fit_constructors: Fitting method constructors

Description

These functions create configuration objects that specify the regression method to be used within calibrate.

Usage

fit_plsr(ncomp, type = c("nwp", "standard", "modified"))
fit_xlsr(ncomp, type = c("nwp", "standard", "modified"), min_w = 3, max_w = 15)

Value

An object of class c("fit_plsr", "fit_constructor") or c("fit_xlsr", "fit_constructor") containing the specified parameters, to be passed to calibrate.

Arguments

ncomp

a positive integer indicating the maximum number of PLS components to use.

type

a character string indicating the algorithm variant. One of "nwp" (default), "standard", or "modified".

• "nwp": replicates the NIRWise PLUS method, which uses correlation-based weights with an additional slope correction applied to the weights and scores.

• "standard": standard PLS using standardised covariances between spectra and reference values as weights.

• "modified": modified PLS using correlations between spectra and reference values as weights.

min_w

a positive integer indicating the minimum window size for the XLS algorithm. Default is 3.

max_w

a positive integer indicating the maximum window size for the XLS algorithm. Must be greater than min_w. Default is 15.

Author

Leonardo Ramirez-Lopez and Claudio Orellano

Details

There are two regression methods available:

Partial least squares (fit_plsr)

Uses PLS regression. The only parameter optimised is the number of components (ncomp). Three algorithm variants are available via type: "nwp", "standard", and "modified".

Extended partial least squares (fit_xlsr)

Uses the XLS algorithm. In addition to ncomp and type, the window range (min_w, max_w) controls the local smoothing applied within the algorithm.

See Also

calibrate, calibrate_models

Examples

# PLS as in NIRWise PLUS
fit_plsr(ncomp = 15)

# Standard PLS with 15 components
fit_plsr(ncomp = 15, type = "standard")

# Modified PLS with 15 components
fit_plsr(ncomp = 15, type = "modified")

# XLS as in NIRWise PLUS
fit_xlsr(ncomp = 10)

# Standard XLS with custom window range
fit_xlsr(ncomp = 10, type = "standard", min_w = 5, max_w = 20)