Apply Savitzky-Golay filters to a Spectra object

This function is a simple wrapper around the function sgolayfilt. It allows one to apply Savitzky-Golay filters to a Spectra object in a convenient way.

sgfSpectra(spectra, m = 0, ...)

Arguments

spectra

An object of S3 class Spectra().

m

The desired m-th derivative. m = 0 smooths the data (i.ei a rolling average), m = 1 gives the first derivative etc.

...

Other parameters to be passed to sgolayfilt.

Value

A object of class Spectra.

See also

Additional documentation at https://bryanhanson.github.io/ChemoSpec/

Author

Bryan A. Hanson (DePauw University).

Examples

# You need to install package "signal" for this example
# This example assumes the graphics output is set to ggplot2 (see ?GraphicsOptions).
if (requireNamespace("signal", quietly = TRUE)) {
  library("ggplot2")
  library("patchwork")
  data(SrE.IR)
  myt1 <- expression(bolditalic(Serenoa) ~ bolditalic(repens) ~ bold(IR ~ Spectra))
  myt2 <- expression(bolditalic(Serenoa) ~ bolditalic(repens) ~ bold(IR ~ Spectra ~ (Smoothed)))

  p1 <- plotSpectra(SrE.IR)
  p1 <- p1 + ggtitle(myt1) + coord_cartesian(xlim = c(1900, 2100), ylim = c(0.0, 0.03))

  sgf <- sgfSpectra(SrE.IR)

  p2 <- plotSpectra(sgf)
  p2 <- p2 + ggtitle(myt2) + coord_cartesian(xlim = c(1900, 2100), ylim = c(0.0, 0.03))

  p3 <- p1/p2
  p3
}
#> Coordinate system already present. Adding new coordinate system, which will
#> replace the existing one.
#> Coordinate system already present. Adding new coordinate system, which will
#> replace the existing one.