spc.fit.poly: Polynomial Baseline Fitting

Description

These functions fit polynomal baselines.

Usage

spc.fit.poly(fit.to, apply.to = NULL, poly.order = 1, 
             short = NULL, user = NULL, date = NULL)
spc.fit.poly.below  (fit.to, apply.to = fit.to, poly.order = 1, npts.min = NULL,
                     noise = 0, 
                     short = NULL, user = NULL, date = NULL)

Arguments

fit.to

hyperSpec object on which the baselines are fitted

apply.to

hyperSpec object on which the baselines are evaluted If NULL, a hyperSpec object containing the polynomial coefficients rather than evaluted baselines is returned.

poly.order

order of the polynomial to be used

npts.min

minmal number of points used for fitting the polynomial

noise

noise level to be considered during the fit. It may be given as one value for all the spectra, or for each spectrum separately.

short, user, date

handed to logentry

Value

hyperspec object containing the baselines in the spectra matrix, either as polynomial coefficients or as polynomials evaluted on the spectral range of apply.to

Details

Both functions fit polynomials to be used as baselines. If apply.to is NULL, a hyperSpec object with the polynomial coefficients is returned, otherwise the polynomials are evaluated on the spectral range of apply.to. spc.fit.poly calculates the least squares fit of order poly.order to the complete spectra given in fit.to. Thus fit.to needs to be cut appropriately. spc.fit.poly.below tries to fit the baseline on appropriate spectral ranges of the spectra in fit.to. For details, see ../doc/baselinebelow.pdf.

Examples

Run this code

baselines <- spc.fit.poly(chondro[,, c (625 ~ 640, 1785 ~ 1800)], chondro)
plot(chondro - baselines, "spcprctl5")

baselines <- spc.fit.poly.below(chondro)
plot(chondro - baselines, "spcprctl5")

vignette ("baselinebelow", package = "hyperSpec")