it is speedier to use sort than a combination of [] and order: N<- 1000000 x <- runif(N) > system.time(x[order(x)[c(N-1,N)]]) user system elapsed 1.03 0.00 1.03 > system.time(sort(x)[c(N-1,N)]) user system elapsed 0.28 0.00 0.28
On Sep 4, 11:17 am, Noah Silverman <n...@smartmediacorp.com> wrote: > Phil, > > That's perfect. (For my application, I've never seen a tie. While > possible, the likelihood is almost none.) > > Thanks! > > -- > Noah > > On 9/3/09 4:29 PM, Phil Spector wrote: > > > > > Noah - > > max(x[-which.max(x)] will give you the second largest value, > > but it doesn't handle ties. > > x[order(x,decreasing=TRUE)[n]] will give you the nth largest > > value, with the same caveat regarding ties. For example, > > x[order(x,decreasing=TRUE)[1:3]] will give you the three largest > > values. > > > - Phil Spector > > Statistical Computing Facility > > Department of Statistics > > UC Berkeley > > spec...@stat.berkeley.edu > > > On Thu, 3 Sep 2009, Noah Silverman wrote: > > >> Hi, > > >> I use the max function often to find the top value from a matrix or > >> column of a data.frame. > > >> Now I'm looking to find the top 2 (or three) values from my data. > > >> I know that I could sort the list and then access the first two > >> items, but that seems like the "long way". Is there some way to > >> access "max_2" or similar? > > >> Thanks! > > >> -- > >> Noah > > >> ______________________________________________ > >> r-h...@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-h...@r-project.org mailing listhttps://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guidehttp://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.