search for: syntx

...(1:10) & b<-c(11:20). I now want to select a subgroup according the values of b. I know if I just want to select, say, b=17, I can use f<-d[d$b==17] and R will give me > f a b 7 7 17 However, if now I want to select a subgroup according to b==e<-c(13,15,17), then the same syntx doesn't work. What is the correct way to do it? My data have more than one million subjects, and I want to select part of them according to their id numbers. Your help will be highly appreciated. Best regards, Yu-Kang