| coda {ptw} | R Documentation |
Chromatogram selection using the CODA algorithm
Description
The CODA algorithm calculates a so-called MCQ (Mass Chromatogram Quality) value for every row of the input. High MCQ values correspond with those chromatograms not containing spikes and/or a baseline.
Usage
coda(x, window = 5, smoothing = c("median", "mean"))Arguments
x |
data matrix containing chromatograms in the rows |
window |
width of the smoothing window |
smoothing |
type of smoothing: whether to use running means or running medians |
Details
The MCQ value of a spectrum is the inner product between the standardized, smoothed chromatogram, and the length-scaled chromatogram. In literature, a cut-off of 0.85 has been reported to work well in selecting useful chromatograms, although this is strongly data-set dependent.
References
Windig, W., Phalp, J., Payna, A. (1996) "A noise and background reduction method for component detection in liquid chromatography/mass spectrometry", Analytical Chemistry, 68, 3602 – 3606.
Examples
data(gaschrom)
coda(gaschrom)