This module is to extract molecular formulas from a database.
UFA_PubChem_formula_extraction(path)Molecular formulas in https://pubchem.ncbi.nlm.nih.gov/ are stored in the provided `path` in the .txt format.
path to store information
Kim S, Chen J, Cheng T, Gindulyte A, He J, He S, Li Q, Shoemaker BA, Thiessen PA, Yu B, Zaslavsky L, Zhang J, Bolton EE. PubChem in 2021: new data content and improved web interfaces. Nucleic Acids Res., 2021 Jan 8; 49(D1):D1388–D1395 , tools:::Rd_expr_doi("10.1093/nar/gkaa971").