pkdecompint: Decomposition of peaks in an interval

In diffractometry: Baseline Identification and Peak Decomposition for x-Ray Diffractograms

Description

Decomposition of peaks in an interval of the diffractogram

Usage

pkdecompint(baslfit, intnum, k, thresh=0, alpha=0.1, heterosk=TRUE,
maxiter=10000, dispers=1, baselim=c(0.05,5))

Arguments

baslfit	Output of baslfit
intnum	Number of interval
k	Number of peak components to fit
thresh	Threshold for residual criterion
alpha	Test level for residual criterion
heterosk	If TRUE, the estimate of noise level given in baslfit is used (default); otherwise noise level is taken to be proportional to signal height
maxiter	Number of attempts to fit a model with k components
dispers	Additional dispersion factor; not used if heterosk==T
baselim	Limits for changes in the baseline estimate; first component is given in percent of the baseline height, second in counts/2theta

Value

Returns a LIST with components

intnr	Number of interval
x	values of 2theta
y	the diffractogram with baseline removed
fit	the resulting fit, evaluated at all points of x
fitpk	a matrix with num.ker rows that contain fits of the individual peak components
basl	the basline estimate as given in baslfit
baslchg	chnage of baseline estimate
rss	residual sum of squares, standardized by noise level estimate
num.ker	number of peak components
par	parameter vector as given in section 8 of Davies et al. (2008)
parbl	intercept and slope of the baseline change
parpks	physical characteristics of the peaks
accept	is the fit accepted by the residual criterion
alpha	test level for residual criterion
thresh	threshold used in residual criterion

Author(s)

T. Mildenberger; Algorithm for residual criterion by T. Bernholt and T. Hofmeister

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

T. Bernholt and T. Hofmeister (2006): "An algorithm for a generalized maximum subsequence problem", in: J. Correa, A. Hevia, M. Kiwi (editors), "Latin 2006: Theoretical Informatics", volume 3887 of Lecture notes in Computer Science, pages 178-189, Berlin, Heidelberg. Springer Verlag

See Also

diffractogram, baselinefit, pkdecomp

Examples

## Decomposition of data in peak interval into two components

set.seed(0)

par(mfrow=c(2,1))

data(indiumoxide)
indox<-indiumoxide[1901:2400,]
base<-baselinefit(indox)

ind<-c(base$indlsep[1],base$indrsep[1])

plot(indox[ind[1]:ind[2],1], 
base$baseline$peaks[ind[1]:ind[2]],xlab="",ylab="")

pks<-pkdecompint(base,intnum=1,k=2)

lines(indox[ind[1]:ind[2],1],pks$fit,col="red")
plot(indox[ind[1]:ind[2],1],pks$fitpk[1,],ylim=c(0,1800),type="l",xlab="",ylab="")
lines(indox[ind[1]:ind[2],1],pks$fitpk[2,])

diffractometry documentation built on March 18, 2018, 1:53 p.m.