找出群中的“顶N”，求R中“顶N”的平均值。

Question

       Rank       Laps   Average Time
1        1          1       30
2        2          1       34
3        3          1       35
4        1          2       32
5        2          2       33        
6        3          2       56
7        4          1       43
8        5          1       23
9        6          1       31
10       4          2       23
11       5          2       88
12       6          2       54

我想知道我如何能够分组排名1-3和4-6，并得到一个平均的“平均时间”的每一圈。另外，如果我有7-9组，10-13组，我也想把它延长.

Answer 1

一种选择是使用cut将不同的级别分组，并将Laps添加为分组变量。然后，您可以对数据进行summarize以获得mean。

library(tidyverse)

df %>%
  group_by(gr = cut(Rank, breaks = seq(0, 6, by = 3)), Laps) %>%
  summarize(avg = mean(Average_Time))

输出

  gr     Laps   avg
  <fct> <int> <dbl>
1 (0,3]     1  33  
2 (0,3]     2  40.3
3 (3,6]     1  32.3
4 (3,6]     2  55  

如果要显示组的级别范围，则为另一个选项：

df %>%
  group_by(gr = cut(Rank, breaks = seq(0, 6, by = 3))) %>%
  mutate(Rank_gr = paste0(min(Rank), "-", max(Rank))) %>% 
  group_by(Rank_gr, Laps) %>% 
  summarize(avg = mean(Average_Time))

输出

  Rank_gr  Laps   avg
  <chr>   <int> <dbl>
1 1-3         1  33  
2 1-3         2  40.3
3 4-6         1  32.3
4 4-6         2  55  

由于您将有不均衡的组，所以您可能需要使用case_when来创建组：

df %>%
  group_by(gr=case_when(Rank %in% 1:3 ~ "1-3",
                        Rank %in% 4:6 ~ "4-6",
                        Rank %in% 7:9 ~ "7-9",
                        Rank %in% 10:13 ~ "10-13"), 
           Laps) %>%
  summarize(avg = mean(Average_Time))

数据

df <- structure(list(Rank = c(1L, 2L, 3L, 1L, 2L, 3L, 4L, 5L, 6L, 4L, 
5L, 6L), Laps = c(1L, 1L, 1L, 2L, 2L, 2L, 1L, 1L, 1L, 2L, 2L, 
2L), Average_Time = c(30L, 34L, 35L, 32L, 33L, 56L, 43L, 23L, 
31L, 23L, 88L, 54L)), class = "data.frame", row.names = c(NA, 
-12L))