> -----Original Message----- > From: r-help-boun...@r-project.org > [mailto:r-help-boun...@r-project.org] On Behalf Of Praveen Surendran > Sent: Wednesday, October 14, 2009 9:15 AM > To: r-help@r-project.org > Subject: [R] Getting indeices of intersecting elements. > > Hi, > > Is there a command to get the indices of intersecting elements of two > vectors as intersect() will give the elements and not its indices.
intersect() uses match() to do that. match(x,y,nomatch) gives the indices of elements of y that elements of x match and match(y,x,nomatch) gives the indices of the elements of x that elements of y match. In each case, the unmatched elements are marked by the value in nomatch. E.g. > x<-letters[1:5] > y<-letters[(1:5)*2] > x [1] "a" "b" "c" "d" "e" > y [1] "b" "d" "f" "h" "j" > match(y,x,nomatch=0) # x[c(2,4)] are in y [1] 2 4 0 0 0 > match(x,y,nomatch=0) # y[c(1,2)] are in x [1] 0 1 0 2 0 (If the second argument contains duplicates the index is for the first of them.) Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com > Thanks in advance. > > > > Praveen Surendran > > School of Medicine and Medical Sciences > > University College Dublin > > Belfield, Dublin 4 > > Ireland. > > > [[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.
