Clusters 2 and 4 highlighted both C-H peaks and the fingerprint region peaks, resembling clusters C and D, respectively. Cluster 6 showed no overlap peaks except for C-H peaks at 3000 cm -1 , consistent with the characteristics of hierarchical cluster F. Although the results of PCA and k-means analysis were similar to those of hierarchical clustering, they did not reveal detailed trends in the classification. Additionally, we explored an alternative approach by digitizing the spectral images using a digitizer, extracting latent variables using a variational autoencoder (VAE), employing dimensionality reduction using PCA, and applying k-means clustering. Details of this analysis are provided in the Supporting Information.