Dataset preparation: We utilized the polymer database available on CROW (), from which we collected data of 44 conventional polymers. The molecular structures of these polymers are shown in Fig. . The number 44 represents a value frequently observed in experimental informatics with a small amount of data. In this study, the unit structure of the polymers was recognized in SMILES format, from which the task of predicting the refractive index was set. The molecular weight and higher-order structures of the polymers were not considered.