Determines if the provided data has intensity type of absorbance or transmittance.
intensity_type(ftir)
a character value 'absorbance' or 'transmittance'
A data.frame of FTIR spectral data including column to be converted. Can't contain both `absorbance` and `transmittance` column as the receiving column would be overwritten
Un data.frame de données spectrales IRTF incluant la colonne à convertir. Ne peut pas contenir les colonnes `absorbance` et `transmittance` car la colonne de réception serait écrasée.