Thank you, David and Gabor, for the creative solutions, and for introducing me to pmin()
Jonathan On Thu, May 20, 2010 at 9:55 PM, Gabor Grothendieck <ggrothendi...@gmail.com > wrote: > Try this one liner. The first argument of rep is the sorted > intersection and the second argument is the calculated from the > parallel minimum of the counts of elements in a that are also in b and > the counts of elements in b that are also in a. > > rep(sort(intersect(a, b)), pmin(table(a[a %in% b]), table(b[b %in% a]))) > > It does have the advantage of not introducing factors. > > On Thu, May 20, 2010 at 6:24 PM, Jonathan <jonsle...@gmail.com> wrote: > > Thanks, but that doesn't quite work, since I'd want the result of b[b > %in% > > a] to be symmetric with a[a%in%b] (so if there are two 2's in EACH > vector, > > I'll get two 2's in the result, but if there are two 2's in only one > vector, > > but one two in the other, the result will show only one 2. > > > > Consider: > > > >> a <- c(2,4,3) > >> b<-c(6,6,5,2,2,8,4) > > > >> b[b %in% a] > > [1] 2 2 4 > > > >> a[a%in%b] > > [1] 2 4 > > > > The second answer is correct, but I can't predict which variable to put > in > > which position in the statement, so I'd need them both to be correct. > > > > Best, > > Jonathan > > > > On Thu, May 20, 2010 at 6:10 PM, David Winsemius <dwinsem...@comcast.net > >wrote: > > > >> > >> On May 20, 2010, at 5:58 PM, Jonathan wrote: > >> > >> Hi all, > >>> The ?intersect entry kindly points out that it discards duplicate > >>> entries. I'm looking, however, to get the intersection while KEEPING > >>> duplicate entries, and there are no instructions on how to accomplish > this > >>> using intersect(). > >>> > >>> Does anybody have any idea how this might be done, or am I going to > need > >>> to > >>> program something from scratch (something like ordering the vectors and > >>> then > >>> looping through them)? > >>> > >>> > >>> > >>> ex: > >>> > >>> a <- c(2,4,2,3) > >>>> b<-c(6,6,5,2,2,8,4) > >>>> intersect(a,b) > >>>> > >>> [1] 2 4 > >>> > >> > >> > b %in% a > >> [1] FALSE FALSE FALSE TRUE TRUE FALSE TRUE > >> > >> # Now use logical indexing on "b" > >> > >> > b[b %in% a] > >> [1] 2 2 4 > >> > >> > >>> > >>> > >>> I'd hope the answer to be 2 2 4. > >>> > >>> Regards, > >>> Jonathan > >>> > >>> [[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. > >>> > >> > >> David Winsemius, MD > >> West Hartford, CT > >> > >> > > > > [[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. > > > [[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.
