r - 如何按顺序按组对值求和

Question

我在 duration 列中有一个包含持续时间值的数据框并将列中的值分组 gaze_focus .

df1
   duration gaze_focus
29    1.011  periphery
31    1.590     center
33    1.582     center
35    0.571  periphery
37    0.561     center
39    2.136     center
41    0.181  periphery
43    1.475     center
45    0.177  periphery
47    0.940  periphery
49    2.102     center

我想计算 的总和紧邻相同组值 得到这个结果:

df2
  duration gaze_focus
1    1.011  periphery
2    3.172     center
3    0.571  periphery
4    2.697     center
5    0.181  periphery
6    1.475     center
7    1.117  periphery
8    2.102     center

我知道可以使用例如按组求和等数学运算 aggregate或 tapply但我不知道如何按小块按组对值求和。帮助表示赞赏!
可重现的数据:

df1 <- structure(list(duration = c(1.011, 1.59, 1.582, 0.571, 0.561, 
2.136, 0.181, 1.475, 0.177, 0.94, 2.102), gaze_focus = c("periphery", 
"center", "center", "periphery", "center", "center", "periphery", 
"center", "periphery", "periphery", "center")), row.names = c(29L, 
31L, 33L, 35L, 37L, 39L, 41L, 43L, 45L, 47L, 49L), class = "data.frame")

Answer 1

一 dplyr选项可以是:

df1 %>%
 group_by(gaze_focus, rleid = with(rle(gaze_focus), rep(seq_along(lengths), lengths))) %>%
 summarise_all(sum) %>%
 arrange(rleid)

  gaze_focus rleid duration
  <chr>      <int>    <dbl>
1 periphery      1    1.01 
2 center         2    3.17 
3 periphery      3    0.571
4 center         4    2.70 
5 periphery      5    0.181
6 center         6    1.48 
7 periphery      7    1.12 
8 center         8    2.10