Nice one Gabor! It works great, and is really simple. Bill Dunlap's solution of
GET$pass.var <- as.name(GET$pass.var) eval(substitute(mean(x), list(x=GET$pass.var))) also works. Thanks! On Tue, Aug 25, 2009 at 12:59 PM, Gabor Grothendieck<ggrothendi...@gmail.com> wrote: > Try this: > > x <- get(GET$pass.var) > mean(x) > > > On Tue, Aug 25, 2009 at 12:26 PM, Ista Zahn<iz...@psych.rochester.edu> wrote: >> Hi everyone, >> I'm building a website (http://yourpsyche.org) using Jeffrey Horner's >> awesome Rapache module. I want to take user input, and pass it to an R >> script. At first I was simply using if else statements, but after a >> while I had so many nested if else's in my code that my head was >> spinning. So then I started using cat() and source() to write >> temporary files and read them back in (see example below). I've >> searched around, and I think there might be a better way to do it with >> substitute(), but I can't seem to figure it out (see attempt below). >> >> Here is a minimal example: >> >>> ###set up simple example### >>> GET <- list(pass.var="b") >>> a <- 1:10 >>> b <- 11:20 >>> >>> ###using if else works but becomes confusing when I have a lot of variables >>> to pass### >>> if(GET$pass.var=="a") >> + { >> + mean(a) >> + } else if(GET$pass.var=="b") >> + { >> + mean(b) >> + } >> [1] 15.5 >>> >>> ###writing to a temporary file works but feels like a hack and results in >>> many temp >> files### >>> cat('print(mean(', GET$pass.var,'))', file="tmp.R",sep="") >>> source("tmp.R") >> [1] 15.5 >>> >>> ###this seems promising but I can't figure it out### >>> substitute(mean(x), list(x=GET$pass.var)) >> mean("b") >>> >>> ###is there a better way?### >>> >> >> Thanks! >> -- >> Ista Zahn >> Graduate student >> University of Rochester >> >> ______________________________________________ >> 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. >> > -- Ista Zahn Graduate student University of Rochester ______________________________________________ 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.
