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Univariate filtering

Functions used to assess individual variables or features independently.

zscore()
Classical or Robust Z-Score
iqrMethod()
Interquartile Range Method
directOutlyingness()
Directional Outlyingness for Skewed Distribution

Multivariate filtering

orthogonalization methods

Functions used to identify and remove unwanted covariance structures and sources of variance from the multivariate data.

epo()
External Parameter Orthogonalization
osc()
Orthogonal Signal Correction
nas()
Net Analyte Signal
opls()
Orthogonal Projections to Latent Structures
o2pls()
Modified Orthogonal Projections to Latent Structures
direct_osc()
Direct Orthogonal Signal Correction
projected_osc()
Projected Orthogonal Signal Correction
yGradientglsw()
y-Gradient Generalized Least Squares Weighting
direct_orthogonal()
Direct Orthogonalization

calibration transfer

Functions used to to transfer a calibration model developed on one instrument to another instrument.

pds()
Piecewise Direct Standardization
glsw()
Generalized Least Squares Weighting

Peak fitting

Functions used to characterize spectral lines. The choice of the fitting function depends on the specific broadening mechanisms and physical conditions of the emitting environment.

peakfit()
Peak Fitting
multipeakfit()
Multiple Peaks Fitting

Data visualization

Functions that help assess data visually.

plotfit()
Plotting of Fitted Spectral Line
plotSpec()
Plotting of Spectra
outlierplot()
Univariate Representation of Multivariate Outliers
adjusted_boxplot()
Adjusted Boxplot
generalized_boxplot()
Generalized Boxplot

Smoothing

Functions used to increase the signal-to-noise ratio.

average()
Fast Average for Large Spectral Dataset

Baseline correction

Functions used to fit and remove the background emission.

whittaker()
Asymmetric Least Squares
baseline_lsp()
Least-Squares Polynomial
baseline_arpls()
Asymmetrically Reweighted Penalized Least Squares

Normalization

samples normalization

Functions used to adjust the systematic differences among samples.

msc()
Multiplicative Signal Correction
normalize()
Spectra Normalization

data scaling

Functions used to adjust each variable/feature by a scaling factor computed based on the dispersion of the variable.

snv()
Standard Normal Variate
pareto()
Pareto Scaling
minmax()
Min-Max Normalization
center()
Data Centering
poisson_scale()
Poisson Scaling

data transformation

Function used to transform variable(s) toward central normality.

robustBCYJ()
Robust Box-Cox and Yeo-Johnson Transformation

Robust statistical estimators

biweight

Functions that use Tukey’s biweight formalism.

biweight_scale()
Biweight Scale
biweight_location()
Biweight Location
biweight_midvariance()
Biweight Midvariance
biweight_midcovariance()
Biweight Midcovariance
biweight_midcorrelation()
Biweight Midcorrelation

tail weight

Functions used to measure the tail weight of a distribution.

quantile_weight()
Quantile Tail Weight Measure
medcouple_weight()
Medcouple Tail Weight Measure

scale

Function used to compute highly robust estimators for scale (or dispersion).

umad()
Unbiased Median Absolute Deviation
rousseeuwCroux()
Rousseeuw-Croux Scale Estimators

Special functions

Functions used for charcaterizing plasma emission in laser spectroscopy.

tukeyGH()
Tukey g-and-h Parametric Distribution
gaussian()
Gaussian Function
lorentzian()
Lorentzian Function
pseudo_voigt()
Pseudo-Voigt Function

Miscellaneous

correlation()
Correlation Coefficients: Pearson, Spearman, Kendall, Chatterjee, and Biweight Midcorrelation
summaryStats()
Classical or Robust Descriptive Statistics