selections of data by one variable
test <- data.frame(cbind(1:10,11:20))
names(test) <- c("a", "b")
test[test$b == 17,]
test[test$b %in% c(13, 15, 17),]
Tu Yu-Kang wrote:
Dear R experts, My problem is as follows: Suppose I have a data frame d comprising two variable a<-c(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
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