Take a look at: >get("%in%")
to see why this (i.e. which(y %in% x) ) is not a good idea. -- Bert On Tue, Feb 12, 2013 at 9:48 AM, Nordlund, Dan (DSHS/RDA) <nord...@dshs.wa.gov> wrote: > Another option is > > which(y %in% x) > > > Dan > > Daniel J. Nordlund > Washington State Department of Social and Health Services > Planning, Performance, and Accountability > Research and Data Analysis Division > Olympia, WA 98504-5204 > >> -----Original Message----- >> From: r-help-boun...@r-project.org [mailto:r-help-bounces@r- >> project.org] On Behalf Of Pascal Oettli >> Sent: Tuesday, February 12, 2013 2:21 AM >> To: Robert Latest >> Cc: r-help@r-project.org >> Subject: Re: [R] Is there a neat R trick for this? >> >> Hello, >> >> ?match >> >> > x <- c(4,5,6) >> > y <- c(10,1,5,12,4,13,14) >> > match(x,y) >> [1] 5 3 NA >> >> Hope this helps, >> Pascal >> >> >> Le 12/02/2013 19:09, Robert Latest a écrit : >> > Hello all, >> > >> > given two vectors X and Y I'd like to receive a vector Z which >> > contains, for each element of X, the index of the corresponding >> > element in Y (or NA if that element isn't in Y). >> > >> > Example: >> > >> > x <- c(4,5,6) >> > y <- c(10,1,5,12,4,13,14) >> > >> > z <- findIndexIn(x, y) >> > z >> > [1] 5 3 NA >> > >> > 1st element of z is 5, because the 1st element of x is at the 5th >> position in y >> > 2nd element of z is 3, because the 2nd element of x is at the 3rd >> position in y >> > 3rd element of z is NA, because the 3rd element of x is not in y >> > >> > Of course I can write the function findIndexIn() using a for loop, >> but >> > in 80% of cases when I felt the urge to use "for" in R it turned out >> > that there was already some builtin operator or function that did the >> > trick. >> > >> > Suggestions, anyone? >> > Thanks, >> > >> > robert >> > >> > ______________________________________________ >> > 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. -- Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm ______________________________________________ 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.