Fig. 1.

Examples of the observed misalignments due to single warping function assumption. Five samples over two m/z bins from each dataset are shown here for demonstration, where the upper and lower rows represent two different m/z bins, respectively (see details in Section 2.1). (a) An example from the Rotterdam dataset shows that even with similar RT, the drift of each sample could be significantly different in two m/z bins. Using only a single warping function, XCMS can only align one bin (the upper one) well but not the other one as shown in the right part. (b) A similar example is also observed in MESA dataset