This function returns current data scale which may be different from the
original data scale (if edata_transform was used).
get_data_scale(omicsObject)an object of the class 'pepData', 'proData', 'metabData',
'lipidData', 'nmrData', 'statRes', or 'trelliData', usually created by
as.pepData, as.proData,
as.metabData, as.lipidData,
as.nmrData, imd_anova, or
as.trelliData respectively.
a character string describing data scale