Yes, this solved the problem. Thanks. Jorge
On 7/27/10 3:13 PM, "Duncan Murdoch" <[email protected]> wrote: > On 27/07/2010 2:34 PM, Jorge A. Ahumada wrote: >> > I am writing a function where the arguments are names of objects or >> variable >> > names in a data frame. To convert the strings to the objects I am using >> > eval(parse(text=name)): >> > >> > f.graph.two.vbs<-function(dataname,v1){ >> > >> > val<-paste(dataname,v1,sep="$") >> > val<-eval(parse(text=val)) >> > val >> > } >> > >> > However running this returns an error: >> > >>> > >f.graph.two.vbs("data","RECORD") >> > Error in data$RECORD : $ operator is invalid for atomic vectors >> > > > That is telling you that the object named data is not a list (or > dataframe), it's an atomic vector. When I create a dataframe named > "data", and run your code, it's fine: so I think this is simply a > scoping error. The value of your function is the same as if you had coded > > data$RECORD > > right in your function, and apparently the data object thus found was > not a dataframe. > > >> > Repeating the individual commands in the workspace does work though.. Do I >> > need to pass the object data in the arguments for this to work? >> > > > No, but you do need to make sure that the variable named by dataname is > visible from within the function, or tell eval() to do the evaluation > somewhere else. I'd guess you want > > val<-eval(parse(text=val), envir=parent.frame()) > > > Duncan Murdoch >> > Thanks, >> > >> > Jorge >> > > > -- Jorge A. Ahumada Technical Director Tropical Ecology Assessment and Monitoring Network (TEAM) Science and Knowledge Division Conservation International 2011 Crystal Dr. Suite 500 Arlington, VA 22202 Phone: 703-341-2543 Mobile: 202-716-3374 http://www.teamnetwork.org/ [[alternative HTML version deleted]] ______________________________________________ [email protected] 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.
