diffractometry (version 0.1-10)

baselinefit: Baseline and peak intervals for diffractometry data

Description

Calculates Taut String and Weighted Smoothing Spline approximations of a diffractogram and identifies the baseline and peak intervals

Usage

baselinefit(data,tau=2.5,gam=1, scl.factor=1.2, maxwdth=5)

Arguments

data

A diffractogram given as a matrix, where the first column gives the angles of diffraction in degrees \(2\theta\) and the second column gives the corresponding photon counts. Angles of diffraction are taken to be equidistant.

tau

Value of Parameter tau used in the residual criterion.

gam

Factor which is used in the separation between peaks and baseline.

scl.factor

Factor which is used in the heteroscedastic residual criterion.

maxwdth

Maximum width of the peaks. By default set to 5 degrees.

Value

Returns a list with components

pmg

Output (list) of the taut string procedure fnpreg(). Contains the estimated fit pmg$fn.

spl

Output (list) of the weighted smoothing spline procedure wsspoiss(). Contains the estimated fit spl$reg.

baseline

Output (list) of the baseline fit procedure basiserg(). Contains the baseline fit baseline$basisl.

npks

Number of peaks.

indlsep

Left indices of the peak intervals.

indrsep

Right indices of the peak intervals.

indextr

Indices of the extreme values.

bs

Output of the weighted smoothing spline precedure for the data with removed peaks. Contains the baseline for non-peak intervals bs$reg.

pks

A vector which contains the data for the peak intervals and zero otherwise.

exb

Output (list) of the routine exber.maxwdth() which computes the peak intervals. Contains again indlsep and indrsep.

x

x values of the data.

y

y values of the data.

References

P.L. Davies, U. Gather, M. Meise, D. Mergel, T. Mildenberger (2008): "Residual based localization and quantification of peaks in x-ray diffractograms", Annals of Applied Statistics, Vol. 2, No. 3, 861-886.. http://www.statistik.tu-dortmund.de/fileadmin/user_upload/Lehrstuehle/MSind/Publikationen/2008/2008_-_Davies_Gather_Meise_Mergel_Mildenberger_-_Residual_based_localization_and_quantification_of_peaks_in_x-ray_diffractograms.pdf

See Also

diffractogram, pkdecomp

Examples

# NOT RUN {
## baseline fit and peak interval identification for a small segment of the indiumoxide data
## baseline plotted in red and data plotted in peak intervals in blue 

data(indiumoxide)
indox<-indiumoxide[1901:2400,]
plot(indox,xlab="",ylab="")
base<-baselinefit(indox)
lines(indox[,1],base$baseline$basisl,col="red")
points(indox[base$indextr,],col="blue") 

# }