Thank you for your time, Don. Exactly what I was looking for - a one-liner. Feedback from others on this post has been good to expand my knowledge, though. I'm too old for homework but have just started using R if/else, loops, and functions and trying to get the hang of them. Best wishes - B
-----Original Message----- From: MacQueen, Don [mailto:macque...@llnl.gov] Sent: Wednesday, September 21, 2016 11:26 AM To: Crombie, Burnette N <bcrom...@utk.edu>; r-help@r-project.org Subject: Re: [R] if/else help Hopefully this is not a homework question. The other responses are fine, but I would suggest the simplest way to do exactly what you ask is if (!exists('r4')) r4 <- data.frame(a=0, b=0, c=0, d='x') The exists() function requires a character string for its first argument, i.e., the name of the object, not the object itself (check the help page for exists). Using "get" to get it doesn't make sense if it already exists. -Don -- Don MacQueen Lawrence Livermore National Laboratory 7000 East Ave., L-627 Livermore, CA 94550 925-423-1062 On 9/20/16, 12:31 PM, "R-help on behalf of Crombie, Burnette N" <r-help-boun...@r-project.org on behalf of bcrom...@utk.edu> wrote: >If a data.frame (r4) does not exist in my R environment, I would like >to create it before I move on to the next step in my script. How do I >make that happen? Here is what I want to do from a code perspective: > >if (exists(r4)) >{ >is.data.frame(get(r4)) >} >else >{ >a <- 0, b <- 0, c <- 0, d <- "x", r4 <- data.frame(cbind(a,b,c,d)) } > >Thanks for your help, >B > > [[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. ______________________________________________ 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.
