John, The intersect() function may help you. For example:
listA <- sort(sample(10, 5)) listB <- sort(sample(10, 5)) both <- intersect(listA, listB) > listA [1] 2 4 7 8 9 > listB [1] 1 2 3 8 10 > both [1] 2 8 Jean On Wed, Sep 16, 2015 at 9:43 PM, John Sorkin <jsor...@grecc.umaryland.edu> wrote: > I have two structures. I think they are lists, but I am not sure. Both > structures contain integers. I am trying to find those members of list b > that are found in list a. I have tried to perform the search using grep, > but I get an error. Please see code below. I would appreciate knowing how > to search listB for any element in listA > Thanks > John > > > > str(listA) > int [1:42] 13083 13705 14123 14168 14382 14652 14654 14678 14817 14822 ... > > str(listB) > int [1:633] 13083 13083 13083 13083 13083 13083 13705 13705 13705 13705 > ... > > grep(listA,listB) > [1] 1 2 3 4 5 6 > Warning message: > In grep(listA, listB) : > argument 'pattern' has length > 1 and only the first element will be used > > > > > > > > > > John David Sorkin M.D., Ph.D. > Professor of Medicine > Chief, Biostatistics and Informatics > University of Maryland School of Medicine Division of Gerontology and > Geriatric Medicine > Baltimore VA Medical Center > 10 North Greene Street > GRECC (BT/18/GR) > Baltimore, MD 21201-1524 > (Phone) 410-605-7119 > (Fax) 410-605-7913 (Please call phone number above prior to faxing) > > > Confidentiality Statement: > This email message, including any attachments, is for ...{{dropped:16}} ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.