Either Dat$c <- ifelse( "Y"==Dat$b, rep( "D", nrow(Dat) ), Dat$a )
Or (more efficiently) Dat$c <- Dat$a Dat$c[ "Y"==Dat$b ] <- "D" Also, beware of creating data frames without using the stringsAsFactors=FALSE option if you plan to replace levels like this. --------------------------------------------------------------------------- Jeff Newmiller The ..... ..... Go Live... DCN:<jdnew...@dcn.davis.ca.us> Basics: ##.#. ##.#. Live Go... Live: OO#.. Dead: OO#.. Playing Research Engineer (Solar/Batteries O.O#. #.O#. with /Software/Embedded Controllers) .OO#. .OO#. rocks...1k --------------------------------------------------------------------------- Sent from my phone. Please excuse my brevity. On October 5, 2015 9:10:29 AM PDT, IOANNA IOANNOU <ii54...@msn.com> wrote: >Hello all, > > > >I have a rather easy question. I want to add a column to the database >which >will change the values of vector a based on the values to vector b. Any >ideas how? > > > >For example: > > > >Dat <- data.frame(a= c('A','A','C','B','D','D','B'), > > b= c('N','N','Y','N','Y','N','N') ) > > > >I want to add a column c which will change 'C' to 'D' if column b is >'Y'. > > > > >> Dat > > a b c > >1 A N A > >2 A N A > >3 C Y D > >4 B N B > >5 C Y D > >6 C N C > >7 B N B > > > > >Any ideas? > > > >Best, > >ioanna > > > > > [[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. ______________________________________________ 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.