search for: datenaissance

Hello I have the following problem : group the lines of a dataframe when no information change (Matricule, Nom, Sexe, DateNaissance, Contrat, Pays) and when the value of Debut of lines i = value Fin of lines i-1 I can obtain it with a do loop. Is it possible to avoid the loop ? The dataframe initial is df1 dput(df1) structure(list(Matricule = c(1L, 1L, 1L, 6L, 6L, 6L, 6L, 6L, 6L, 8L, 8L, 8L, 8L, 8L, 8L, 8L, 8L, 8L, 934L, 934L...