摘要：第一种 > mydata <- data.frame(x1 = c(2,2,6,4),x2 = c(3,4,2,8)) > mydata x1 x2 1 2 3 2 2 4 3 6 2 4 4 8 > mydata$sumx <- mydata$x1 + mydata$x2 > mydata x1 阅读全文

摘要：创建数据框，然后根据给定ID提取对应行的信息，特别是给定的ID比较多的时候，其实很简单！ > patientID <- c("A","B","C","D") > age <- c(25,34,44,52) > DB <- c("T1","T2","T1","T1") > status <- c("P 阅读全文