It is not clear to me what you mean, but: > grep ("x1 \\+.* \\+ x3",test, value = TRUE) [1] "x1 + x2 + x3"
## This will miss "x1 + x3" though. seems to do what you want, maybe. Perhaps you need to read up about regular expressions and/or clarify what you want to do. Cheers, Bert Bert Gunter "The trouble with having an open mind is that people keep coming along and sticking things into it." -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) On Tue, Mar 21, 2017 at 4:50 PM, Joe Ceradini <joecerad...@gmail.com> wrote: > Hi Folks, > > Is there a way to find "x1 + x2 + x3" given "x1 + x3" as the pattern? > Or is that a ridiculous question, since I'm trying to find something > based on a pattern that doesn't exist? > > test <- c("x1", "x2", "x3", "x1 + x2 + x3") > test > [1] "x1" "x2" "x3" "x1 + x2 + x3" > > grep("x1 + x2", test, fixed=TRUE, value = TRUE) > [1] "x1 + x2 + x3" > > > But what if only have "x1 + x3" as the pattern and still want to > return "x1 + x2 + x3"? > > grep("x1 + x3", test, fixed=TRUE, value = TRUE) > character(0) > > I'm sure this looks like an odd question. I'm trying to build a > function and stuck on this. Rather than dropping the whole function on > the list, I thought I'd try one piece I needed help with...although I > suspect that this question itself probably does bode well for my > function :) > > Thanks! > Joe > > ______________________________________________ > 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.