Samuel wrote: > Hi, > > I'm quite fresh to R, and a layman of English as well. I hope I can make you > understood. > > Now I have two vectors A and B. Is there any quick way to know whether B is > a subset of A? and If B is a subset of A, can I know easily which elements > in A (the index of A) equals to B's elements accordingly? > > For example, > > >> a<-1:20 >> b=c(2,5,9,7,4,8,3) >> >> > > Question 1: we know b is a subset of a, but how does R know that? > > Question 2: since we know b is a subset of a, then which a's elements equals > to b? I do it like this: > > test=0 > >> for (i in 1:length(b)) test[i]=which(a==b[i]) >> test >> >> > > Is there any easier way to know these indexes? > > Thanks a lot for you helps in advance > > > a<-1:20 > b<-c(2,5,9,7,4,8,3) > !length(setdiff(b,a)) [1] TRUE > a %in% b [1] FALSE TRUE TRUE TRUE TRUE FALSE TRUE TRUE TRUE FALSE FALSE FALSE [13] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE > which(a %in% b) [1] 2 3 4 5 7 8 9
-- O__ ---- Peter Dalgaard Ă˜ster Farimagsgade 5, Entr.B c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907 ______________________________________________ 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.