A loading related to gypsum

 Following the chain of posts related to gypsum in the soil samples, we continue calculating the principal components of the sample set, and plotting the 5 firsts loadings, after we draw vertical lines where the reference gypsum spectrum has the main peaks, and we can see that the 5th loading (light blue) shows clearly the gypsum peaks.

matplot(rownames(pcspectra_snvdt$rotation),
        pcspectra_snvdt$rotation[ ,1:5], 

        type = "l", main = "Loadings spectra", 

        ylab = "Absorbance", xlab = "wavelength" )

abline(v = c(994, 1204, 1445, 1489, 1537, 1748, 

             1944, 2215, 2266), col = "green", 

       lty = "dotted")