It may be that single and efficient are opposing goals. Two steps lets you create the subset and then just order each query. Alternatively, if the data do not change often, create an ordered version and query that.
David Carlson ----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of Noah Silverman Sent: Friday, July 5, 2013 2:47 PM To: Rui Barradas Cc: R-help@r-project.org Subject: Re: [R] Subset and order That would work, but is painfully slow. It forces a new sort of the data with every query. I have 200,000 rows and need almost a hundred queries. Thanks, -N On Jul 5, 2013, at 12:43 PM, Rui Barradas <ruipbarra...@sapo.pt> wrote: > Hello, > > Maybe like this? > > subset(x[order(x$a), ], b == 3) > > > Hope this helps, > > Rui Barradas > > Em 05-07-2013 20:33, Noah Silverman escreveu: >> Hello, >> >> I have a data frame with several columns. >> >> I'd like to select some subset *and* order by another field at the same time. >> >> Example: >> >> a b c >> 1 2 3 >> 3 3 4 >> 2 4 5 >> 1 3 4 >> etc. >> >> >> I want to select all rows where b=3 and then order by a. >> >> To subset is easy: x[x$b==3,] >> To order is easy: x[order(x$a),] >> >> Is there a way to do both in a single efficient statement? >> >> Thanks, >> >> >> >> -- >> Noah Silverman, M.S., C.Phil >> UCLA Department of Statistics >> 8117 Math Sciences Building >> Los Angeles, CA 90095 >> >> >> >> >> [[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. ______________________________________________ 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.
