diffractometry (version 0.1-10)

pkdecompint: Decomposition of peaks in an interval

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

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

# NOT RUN {
## 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,])

# }