1、读取数据集。这里以一个简单的数据集为例。stu_data屏顿幂垂=data.frame(group=c("1班"荑樊综鲶,"2班","2班","1班","1班","2班"),age=c(">18","16-18","<16","16-18","16-18","16-18"),sex=c("F","M","F","F","M","M"),score=c(100,92,91,88,75,66))
3、利用names(stu_data)，查看数据框的列名，然后按照列名选取数据。stu_data$group #选取group这一列的数据vars=c("age","score") stu_data[,vars] #根据vars中的列名选取多列数据
5、按照数据值选择数据。stu_data[stu_data$group=="1班",] #选取"1班”的数据。
