Question

这是我以前从未见过的很棒的东西。您可以在一个命令中进行汇总，从而等效于mutate，group by和summarize。

aggregate(state.x77,
          list(Region = state.region,
               Cold = state.x77[,"Frost"] > 130), mean)

我想以公式格式复制它。我快到了。

state <- as.data.frame(state.x77)
state$states <- rownames(state.x77)
state$region <- state.region
aggregate(Population ~ region + (state[,"Frost"] > 130), state, mean)

我想给新列起一个名字。我尝试了AS "Cold"，但是没有用。

Answer 1

您还可以在公式界面中使用cbind重命名输入或分组变量：

aggregate(Population ~ region + cbind(cold = Frost > 130), data=state, mean)
#         region  cold Population
#1     Northeast FALSE  8802.8000
#2         South FALSE  4208.1250
#3 North Central FALSE  7233.8333
#4          West FALSE  4582.5714
#5     Northeast  TRUE  1360.5000
#6 North Central  TRUE  2372.1667
#7          West  TRUE   970.1667

在~的两侧工作，并在LHS的一个cbind中使用多个变量：

aggregate(cbind(popn=Population,incm=Income) ~ cbind(cold = Frost > 130), data=state, mean)
#   cold     popn     incm
#1 FALSE 5494.853 4345.412
#2  TRUE 1593.500 4627.875

否则，如果您需要应对这种可能性，只需在RHS上添加多个cbind语句：

aggregate(cbind(popn=Population,incm=Income) ~ cbind(cold = Frost > 130) + 
                                               cbind(st = states), data=state, mean)
#    cold             st  popn incm
#1  FALSE        Alabama  3615 3624
#2   TRUE         Alaska   365 6315
#3  FALSE        Arizona  2212 4530
#4  FALSE       Arkansas  2110 3378
#...

Answer 2

我们可以使用transform

aggregate(Population ~ region + Cold, transform(state, Cold = Frost > 130),   mean)
#        region  Cold Population
#1     Northeast FALSE  8802.8000
#2         South FALSE  4208.1250
#3 North Central FALSE  7233.8333
#4          West FALSE  4582.5714
#5     Northeast  TRUE  1360.5000
#6 North Central  TRUE  2372.1667
#7          West  TRUE   970.1667

如何为列名创建别名？

2 个答案: