Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com
> -----Original Message----- > From: r-help-boun...@r-project.org > [mailto:r-help-boun...@r-project.org] On Behalf Of Dimitri Shvorob > Sent: Thursday, August 26, 2010 3:16 AM > To: r-help@r-project.org > Subject: [R] Quick GREP challenge > > > > grep("f[0-9]+=", "f1=5,f22=3,", value = T) > [1] "f1=5,f22=3," > > How do I make the line output c("f1", "f22") instead? > (Actually, c(1,22) > would be even better). If you had S+ you could use subpattern and keep arguments to strsplit (which otherwise acts like R's strsplit): > strings <- c("f1=5,f22=3,", "g4,f55,f66", "hello") > strsplit(strings, "f([[:digit:]]+)", subpattern=1, keep=TRUE) [[1]]: [1] "1" "22" [[2]]: [1] "55" "66" [[3]]: character(0) keep=TRUE means to split the string by what is not in the pattern (keeping what is in the pattern) instead of the usual splitting by what is in the pattern and keeping what is not in the pattern. subpattern=n means to match by the whole pattern but to use only the n'th parenthesized subpattern when deciding what to split by or keep. In this case the whole pattern matches 'f' followed by 1 or more digits but we only want the keep the digits. (subpattern=0, the default, means to use the entire pattern.) You still need to use as.integer() or as.numeric() on the output elements. Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com > > > Thank you. > > > -- > View this message in context: > http://r.789695.n4.nabble.com/Quick-GREP-challenge-tp2339486p2 339486.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > 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.
