List of two data.tables with possible columns base, sd, amp,
and phase, depending on the columns in diffFeatureGroups.
Arguments
diffFeatureGroups
data.frame with optional columns meanBase,
dBase, meanSd, dSd, meanAmp, dAmp, meanPhase, and dPhase
describing the changes in abundance between two conditions. Each row
corresponds to a group of features.
checkValid
Logical for whether to only return rows for which both
amplitudes are greater than or equal to zero and both standard deviations
are greater than zero.