如何同时订购两列

Question

我希望“YEAR”列按“1970,1971,1972,1973”的顺序排列，而“AMOUNT”列应同时按升序排列。另外，我想创建额外的行来完成“YEAR”列中的年数。

K <- data.frame("YEAR" = c(1970,1972,1973,1971,1972,1971,1973,1970,1970),
"AMOUNT" = c(100,100,200,100,400,300,700,200,800),
"DISTANCE" = c(12,3,9,12,25,26,10,7,15))

这是我想要的结果：

K <- data.frame("YEAR" = c(1970,1971,1972,1973,1970,1971,1972,1973,1970,1971,1972,1973),
                "AMOUNT" = c(100,100,100,200,200,300,400,700,800,"NA","NA","NA"),
                "DISTANCE" = c(12,3,12,9,7,26,25,10,15,"NA","NA","NA"))