Hi Chun, >> I did do the research and work on for hours ... I try to creat a new >> variable in my dataset.
Yes, looks like you did. Look at ?interaction, which gives you more flexibility than ?":". ## Example diet<-sort(rep(x=c("C","T"),4)) vesl<-rep(x=c("A","P"),4) mydata<-data.frame(diet,vesl) mydata$trt <- interaction(mydata$diet, mydata$vesl) mydata mydata$trt <- mydata$diet:mydata$vesl mydata Regards, Mark. Chun-Hao Tu wrote: > > > > Hi R users, > > I did do the research and work on for hours, but I still don't know how to > solve my silly problem. I try to creat a new variable in my dataset. > > such as if diet=="C" && vesl=="P" then trt="CP"; if diet=="C" && > vesl=="A" then trt="CA";..... The following is my code (It does not work > correctly). > > Could anyone give me a hint? Appreciate! > > > >> diet<-sort(rep(x=c("C","T"),4)) >> vesl<-rep(x=c("A","P"),4) >> mydata<-data.frame(diet,vesl) >> >> mydata$trt<-ifelse(mydata$diet=="C" && mydata$vesl=="A", "CA", > + ifelse(mydata$diet=="C" && mydata$vesl=="P", "CP", > + ifelse(mydata$diet=="T" && mydata$vesl=="A", "TA", > + ifelse(mydata$diet=="T" && mydata$vesl=="P", "TP")))) >> mydata > diet vesl trt > 1 C A CA > 2 C P CA > 3 C A CA > 4 C P CA > 5 T A CA > 6 T P CA > 7 T A CA > 8 T P CA > > > > Thank you very much > > > > Chunhao > > _________________________________________________________________ > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list > 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. > > -- View this message in context: http://www.nabble.com/error-bars-tp22092367p22096172.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list 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.