Another possibility: df$Date[match(1800, df$myvalue)]
match() stops at the first value encountered so it may be a bit faster than a full subset(), depending on your table size. Another difference: this approach would return NA if there was no match, subset(...)[1, ] would trigger an error. Depends what your needs are. On Thu, Jan 19, 2012 at 7:03 PM, Jorge I Velez <jorgeivanve...@gmail.com> wrote: > Hi ikuzar, > > Try > > subset(df, myvalue == 1800, select = Date)[1, ] > > See ?subset for more information. > > HTH, > Jorge.- > > > On Thu, Jan 19, 2012 at 6:42 PM, ikuzar <> wrote: > >> Hi, >> I 'd like to select the Date where myvalue =1800 appears the* first time*. >> >> For instance: >> df =data.frame(date, myvalue, ...) >> >> ... >> >> Date myvalue >> 2012-01-05 2500 >> 2012-01-06 2450 >> *2012-01-07 1800* >> 2012-01-08 2200 >> 2012-01-09 1800 >> >> I'd like to retrieve the third line. >> >> I do not find a clean way. >> >> Thanks for your help >> >> >> >> -- >> View this message in context: >> http://r.789695.n4.nabble.com/dataframe-how-to-select-an-element-from-a-row-tp4311881p4311881.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. >> > > [[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.
