We introduce a novel suite of informatics tools for the quantitative analysis of NMR metabolomic profile data. The core of the processing cascade is a novel peak alignment algorithm, called hierarchical Clusterbased Peak Alignment (CluPA). The algorithm aligns a target spectrum to the reference spectrum in a topdown fashion by building a hierarchical cluster tree from peak lists of reference and target spectra and then dividing the spectra into smaller segments based on the most distant clusters of the tree. To reduce the computational time to estimate the spectral misalignment, the method makes use of Fast Fourier Transformation (FFT) crosscorrelation. Since the method returns a highquality alignment, we can propose a simple methodology to study the variability of the NMR spectra. For each aligned NMR data point the ratio of the betweengroup and withingroup sum of squares (BWratio) is calculated to quantify the difference in variability between and within predefined groups of NMR spectra. This differential analysis is related to the calculation of the Fstatistic or a oneway ANOVA, but without distributional assumptions. Statistical inference based on the BWratio is achieved by bootstrapping the null distribution from the experimental data. See Vu et al. (2011)<DOI:10.1186/1471210512405> for further information.
Package details 


Author  Trung Nghia Vu, Kris Laukens and Dirk Valkenborg 
Maintainer  Trung Nghia Vu <[email protected]> 
License  Apache License 2.0 
Version  1.2.3 
URL  https://github.com/nghiavtr/speaq 
Package repository  View on GitHub 
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