Hello, I have the following question: when creating a data.frame a1<-c(1,2,3) a2<-c(1,2,3) c<-data.frame(a1,a2) I can select columns using an index like: c[,1:2] Is this possible too when using column-names? (something like c(,"a1":"a2"), which doesn't work)
Alternative question: Is there a function to get the index of a variable by name or can I select certain columns using a loop? (a_1, a_2, ..., a_n) Thank you very much! David [[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.