> grep("f[0-9]+=", "f1=5,f22=3,", value = T) [1] "f1=5,f22=3," How do I make the line output c("f1", "f22") instead? (Actually, c(1,22) would be even better). Thank you. -- View this message in context: http://r.789695.n4.nabble.com/Quick-GREP-challenge-tp2339486p2339486.html Sent from the R help mailing list archive at Nabble.com.