Comparelcms simengine
Purpose
Select variables that are different between related data sets, e.g. mass chromatograms from LC/MS data of different batches.
Synopsis
- y=comparelcms_simengine(data,filter_width)
Description
COMPARELCMS_SIMENGINE determines which variables are different between different data sets. For example, after applying coda_dw to LC/MS data sets of highly related samples, such as the data of a good and a bad batch, the results will be very similar. comparelcms_engine takes the next step and extracts the mass chromatograms that are different. This function is normally not called by itself but by the function comparelcms_sim_interactive. The input argument data is a data cube with mode 1 the number of samples, mode two the number of spectra and mode 3 the number of variables, The optional input argument filter_width is used to smooth the columns of the data set in order to minimize the effect of small shifts, The output argument y contains the similarity indices of the variables. Variables with a low similarity index show the differences between the data sets.
Examples
Determination of similarity indices with a filter of 7 data points.
y=comparelcms_simengine(data,7)
Algorithm
The calculations are based on a similarity index of the minimum of the chromatograms (across the samples) and the maximum of the chromatograms.