Hi, If I have two datasets like this: df=data.frame("id"=rep(1:10,10, each=10), "item1"=sample(1:20, 100, replace=T) df2=data.frame("a"=c(8, 8,10,9, 5, 1,2,1), "b"=c(16,18,11, 19,18, 11,17,12))
How do I find out which ids in the df dataset that has a match for both the numbers occuring in the same row in the df2 dataframe? In the output I would like to get the matching id and the rownumber from the df2. Output something like this Id Rownr 2 1 5 1 7 4 My actual problem is more complex with even more columns to be matched and the datasets are large, hence the solution needs to be efficient. Kind regards, N?r du skickar e-post till Karolinska Institutet (KI) inneb?r detta att KI kommer att behandla dina personuppgifter. H?r finns information om hur KI behandlar personuppgifter<https://ki.se/medarbetare/integritetsskyddspolicy>. Sending email to Karolinska Institutet (KI) will result in KI processing your personal data. You can read more about KI's processing of personal data here<https://ki.se/en/staff/data-protection-policy>. [[alternative HTML version deleted]] ______________________________________________ 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.