Hi, an alternative to parse() is to use quote and bquote,
set.seed(123) d = data.frame(a=letters[1:5], b=1:10, c=sample(0:1, 10, repl=TRUE)) cond1 <- quote(a=="b") cond2 <- quote(b < 6) cond3 <- bquote(.(cond1) & .(cond2)) subset(d, eval(cond1)) subset(d, eval(cond2)) subset(d, eval(cond3)) HTH, baptiste 2009/12/1 William Dunlap <wdun...@tibco.com>: >> -----Original Message----- >> From: r-help-boun...@r-project.org >> [mailto:r-help-boun...@r-project.org] On Behalf Of Santosh >> Sent: Tuesday, December 01, 2009 7:39 AM >> To: r-help@r-project.org >> Subject: Re: [R] "subset" or "condition" as argument to a function >> >> Dear R gurus.. >> I had tried out some suggestions sent to me privately..and >> unfortunately, >> they did not work.. >> >> To use a condiition in a subset, the associated dataframe needs to be >> attached and detached, which I found cumbersome to use if >> using more than 1 >> dataframe (with different dimensions) with same condition. I >> would highly >> appreciate your suggestions to overcome this problem.. Please >> see my example >> of usage I am trying to implement. Please note that the >> "cond' takes in the >> character instead of logical values... >> >> cond1 <- 'group==1&sales>200' >> cond2 <- 'group==2&sales>200' >> cond3 <- 'group==3&sales>200' >> >> d1 <- subset(dat,subset=cond1) >> plot(y~x,data=dat,subset=cond1,type='b') > > The subset argument to plot (and many similar functions) > must be given as a literal expression, not a string that > could be parsed into an expression nor the name of an object > containing an expression nor a function call that evaluates > to an expression. This design is handy for interactive > use but painful in programatic use. One way to deal with > it is to use do.call, which evaluates all the arguments to > the function and then calls the function with the arguments > given literally. Replace the above plot call with > do.call("plot", list(y~x,data=dat,subset=parse(text=cond1),type='b')) > and see if you get what you want. > > Bill Dunlap > Spotfire, TIBCO Software > wdunlap tibco.com > >> lines(y~x,data=dat,subset=cond2) >> points(y~x,data=dat,subset=paste(cond1,cond2,sep='&'),col='blue') >> points(y~x,data=d1,subset=cond3,col='red') >> >> If I try the above, I get the following error message: >> *Error in subset.data.frame(dat, cond) : 'subset' must >> evaluate to logical* >> >> If you could also suggest references implementing similar >> code, I would >> highly appreciate it. >> Thanks so much, >> >> Santosh >> >> On Mon, Nov 23, 2009 at 6:38 PM, Santosh >> <santosh2...@gmail.com> wrote: >> >> > Thanks... I would try it out.. >> > -santosh >> > >> > >> > On Sat, Nov 21, 2009 at 12:04 AM, Bernardo Rangel Tura < >> > t...@centroin.com.br> wrote: >> > >> >> On Fri, 2009-11-20 at 17:40 -0800, Santosh wrote: >> >> > Dear Rxperts! >> >> > >> >> > I was wondering if it is possible to write a function >> which can take in >> >> > argument of a subset or condition.. Of course, I am aware of the >> >> alternate >> >> > methods like coplot, par.plot, xyplot etc... I am specifically >> >> interested in >> >> > using conditions/subsets with "plot".. >> >> > >> >> > A simple fragmented example is shown here.. >> >> > >> >> > pltit <- function(y,x,dat,dat1,dat2,sbst) { >> >> > plot(y~x, data=dat, subset=sbst) >> >> > lines(y~x,data=dat1, subset=subst) >> >> > points(y~x,data=dat2,subset=subst) >> >> > } >> >> > >> >> > pltit(profit,weeks,dat=zone1, sbst='group==1&sales>200') >> >> > >> >> > Could you also suggest pointers/references/examples on >> efficient ways to >> >> > plot simulated data overlaid with observed data? >> >> > >> >> > Have a good weekend! >> >> >> >> >> >> >> > >> >> [[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. > ______________________________________________ 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.
