Are you perhaps needing to (re-)read the discussion on indexing in the "Introduction to R" document that comes with the software? (That is a common deficiency...)
It looks to me like you want something like MVAR <- "population" tab[[ MVAR ]] -- Sent from my phone. Please excuse my brevity. On February 3, 2016 10:23:12 AM PST, Amoy Yang via R-help <r-help@r-project.org> wrote: >population is the field-name in data-file (say, tab). MVAR<-population >takes data (in the column of population) rather than field-name as done >in SAS: %let MVAR=population; >In the following r-program, for instance, I cannot use ... >tab$MVAR...or simply MVAR itself since MVAR is defined as "population" >with double quotes if using MVAR<-c("population") > >On Wednesday, February 3, 2016 11:54 AM, Duncan Murdoch ><murdoch.dun...@gmail.com> wrote: > > > On 03/02/2016 12:41 PM, Amoy Yang via R-help wrote: >> There is a %LET statement in SAS: %let MVAR=population; Thus, MVAR >can be used through entire program. >> In R, I tried MAVR<-c("population"). The problem is that MAVR comes >with double quote "...." that I don't need. But MVAR<-c(population) did >NOT work out. Any way that double quote can be removed as done in SAS >when creating macro_var? >> Thanks in advance for helps! > >R doesn't have a macro language, and you usually don't need one. > >If you are only reading the value of population, then > >MAVR <- population > >is fine. This is sometimes the same as c(population), but in general >it's different: c() will remove some attributes, such as >the dimensions on arrays. > >If you need to modify it in your program, it's likely more >complicated. >The normal way to go would be to put your code in a function, and have >it return the modified version. For example, > >population <- doModifications(population) > >where doModifications is a function with a definition like > >doModifications <- function(MAVR) { > # do all your calculations on MAVR > # then return it at the end using > MAVR >} > >Duncan Murdoch > > > > [[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. [[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.