Formula syntax is different from regular syntax, it is "quoted" and not evaluated in the same way as regular commands (otherwise operations like '+' and '-' would do very different things).
For what you are trying to do, I would suggest creating the formula as a string using paste or sprintf, then use as.formula on that string. You can also use the substitute function, but that tends to be a bit more complicated. -- Gregory (Greg) L. Snow Ph.D. Statistical Data Center Intermountain Healthcare greg.s...@imail.org 801.408.8111 > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-boun...@r- > project.org] On Behalf Of Patrick McKann > Sent: Wednesday, January 05, 2011 8:26 AM > To: r-help@r-project.org > Subject: [R] get() within a command, specifically lmer > > Hello all. Why doesn't this work? > > d=data.frame(y=rpois(10,1),x=rnorm(10),z=rnorm(10),grp=rep(c('a','b'),e > ach=5)) > library(lme4) > model=lmer(y~x+z+(1|grp),family=poisson,data=d) > update(model,~.-z)###works, removes z > var='z' > update(model,~.-get(var))##doesn't remove z > update(model,~. -get(var,pos=d))###doesn't remove z > > I am trying to remove z from the model in the update, but I can't do it > using get(), which is what I would like to do for a more complicated > program. There's something about environments and get() that I don't > understand. > > Any suggestions? > > Thanks. > > [[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. ______________________________________________ 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.
