simspec: Simulate Spectra

In kuwisdelu/matter: Scientific computing for out-of-memory signals and images

Simulate Spectra

Description

Simulate spectra from noise and a list of peaks.

Usage

simspec(n = 1L, npeaks = 50L,
	x = rlnorm(npeaks, 7, 0.3), y = rlnorm(npeaks, 1, 0.9),
	domain = c(0.9 * min(x), 1.1 * max(x)), size = 10000,
	sdx = 1e-5, sdy = sdymult * log1p(y), sdymult = 0.2,
	sdnoise = 0.1, resolution = 1000, fmax = 0.5,
	baseline = 0, decay = 10, units = "relative")

simspec1(x, y, xout, peakwidths = NA_real_,
	sdnoise = 0, resolution = 1000, fmax = 0.5)

Arguments

n	The number of spectra to simulate.
npeaks	The number of peaks to simulate. Not used if x and y are provided.
x, y	The locations and values of the spectral peaks.
xout, domain	The output domain variable or its range.
size	The number of samples in each spectrum.
sdx	The standard deviation of the error in the observed locations of peaks, in units indicated by units.
sdy	The standard deviation(s) for the distributions of observed peak values on the log scale.
sdymult	A multiplier used to calculate sdy based on the mean values of the peaks; used to simulate multiplicative variance. Not used if sdy is provided.
sdnoise	The standard deviation of the random noise in the spectra on the log scale.
resolution	The resolution as defined by x / dx, where x is the observed peak location and dx is the width of the peak at a proportion of its maximum height defined by fmax (defaults to full-width-at-half-maximum – FWHM – definition).
fmax	The fraction of the maximum peak height to use when defining the resolution.
peakwidths	The peak widths at fmax. Typically, these are calculated automatically from resolution.
baseline	The maximum intensity of the baseline. Note that baseline=0 means there is no baseline.
decay	A constant used to calculate the exponential decay of the baseline. Larger values mean the baseline decays more sharply.
units	The units for sdx. Either "absolute" or "relative".

Value

Either a numeric vector of the same length as size, giving the simulated spectrum, or a size x x matrix of simulated spectra.

Author(s)

Kylie A. Bemis

Examples

set.seed(1)
y <- simspec(2)
x <- attr(y, "domain")

plot(x, y[,1], type="l", ylim=c(-max(y), max(y)))
lines(x, -y[,2], col="red")

kuwisdelu/matter documentation built on May 11, 2024, 9:15 a.m.