为两个最高观察值创建指标？

Question

我正在使用以下数据框：

Month      Week   Y     Name   Color
January     2     1.2    Joe    Red
January     2     3.3    Eric   Red
January     2     4.5    Mike   Blue
January     2     1.7    Brian  Blue
January     2     2.9    Pete   Red
January     3     4.6    Joe    Red
January     3     5.1    Eric   Blue
January     3     2.1    Mike   Blue
January     3     6.9    Pete   Red
...

我想创建一个新列（“最高”），用于标识在给定周内具有两个最高 Y 值的个人（用 A 和 B 标识他们，这样以后在我的项目中创建线段会更容易) 谁也有“蓝色”的颜色。

Month      Week   Y     Name    Highest
January     2     1.2    Joe       -
January     2     3.3    Eric      B
January     2     4.5    Mike      A
January     2     1.7    Brian     -
January     2     2.9    Pete      -
January     3     4.6    Joe       -
January     3     5.1    Eric      B
January     3     2.1    Mike      A
January     3     6.9    Pete      -
...

此外，如您在上表中所见，我希望“最高”列在整个月内保持相同 - 该列应显示第 2 周所有观察值中两个 Y 值最高的个体给定月份。我假设这需要group_by(Month, Week) %>%

Answer 1

您可以通过Y 值arrange 数据并将'A'、'B' 分配给前两个值。

library(dplyr)

df %>%
  arrange(Month, Week, desc(Y)) %>%
  group_by(Month, Week) %>%
  mutate(Highest = c('A', 'B', rep(NA, n()-2)))
  #If you want to have '-' instead of `NA`. 
  #mutate(Highest = c('A', 'B', rep('-', n()-2)))