Hi Rui, This is a great help. Thank you, Kai On Tuesday, November 15, 2022 at 11:48:12 AM PST, Rui Barradas <ruipbarra...@sapo.pt> wrote: Às 19:39 de 15/11/2022, Kai Yang escreveu: > Hello Rui, > Yes, it should be the one I want. I modified the code as: > > for(i in grep("data", names(df))) { > try2.un$ab2 <- > ifelse(grepl("ab2", [i]), [i], NA) > } > > But I got error message: > Error: unexpected '[' in: > " try2.un$ab2 <- > ifelse(grepl("ab2",[" > > I think I use [i] in a wrong way. Do you have any suggestion? > Thanks, > Kai On Tuesday, November 15, 2022 at 10:54:08 AM PST, Rui Barradas > <ruipbarra...@sapo.pt> wrote: > > Às 16:18 de 15/11/2022, Kai Yang via R-help escreveu: >> Hi Team, >> I can write a for loop like this: >> for (i in columns(df)){ >> ...... >> } >> >> But it will working on all column in dataframe df. If I want to work on some >> of specific fields (say: the fields' name content 'date'), how should I >> modify the for loop? I changed the code below, but it doesn't work. >> for (i in columns(df) %in% 'date' ){ >> ..... >> } >> >> >> Thank you, >> Kai >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. > Hello, > > Something like this? > > > for(i in grep("date", names(df))) { > # > } > > > Hope this helps, > > Rui Barradas > > Hello,
For what I understand of the problem any of the two below does what the posted code seems to be trying to do. The first is better, no ifelse. for(i in grep("data", names(df))) { is.na(try2.un$ab2) <- !grepl("ab2", df[[i]]) } for(i in grep("data", names(df))) { try2.un$ab2 <- ifelse(grepl("ab2", df[[i]]), df[[i]], NA) } Hope this helps, Rui Barradas [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.