> -----Original Message----- > From: r-help-boun...@r-project.org > [mailto:r-help-boun...@r-project.org] On Behalf Of Dennis Murphy > Sent: Thursday, May 19, 2011 11:38 AM > To: infoc...@gmx.net > Cc: r-help@r-project.org > Subject: Re: [R] vectorial search for elements with certain attributes > > Hi: > > Here's one possible approach: > > A <- c(1,3,7,8,10) > B <- c(5,8) > apply(outer(A, B, '-'), 2, function(x) min(which(x >= 0))) > [1] 3 4
Using findInterval() or as.integer(cut()) would use quite a bit less memory and time for long vectors. findInterval would be more direct, but I think it insists on using ">" instead of ">=" in the above code.cut() lets you choose. > as.integer(cut(c(5, 8, 8.01), A, right=TRUE))+1 [1] 3 4 5 > as.integer(cut(c(5, 8, 8.01), A, right=FALSE))+1 [1] 3 5 5 > findInterval(c(5, 8, 8.01), A) + 1 [1] 3 5 5 Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com > > HTH, > Dennis > > On Thu, May 19, 2011 at 2:58 AM, <infoc...@gmx.net> wrote: > > I have 2 vectors A and B. For each element of B I'd like to > find the index of the next higher or equal element in A. And > I'd like to store it effectiv. E.g.: > > A <- c(1,3,7,8,10) > > B <- c(5,8) > > > > result: 3, 4 > > > > I have a possibility but for long vectors it works not very > effectiv: > > > > ans <- sapply(B, function(x) which.max(A[A < x]) ) > > as.integer(ans + 1) > > > > Is there anyone how has a better idea? > > Thank you for your help, > > Thomas. > > -- > > > > ______________________________________________ > > 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. > ______________________________________________ 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.
