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 [[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.