r - 用 1 填充列直到找到值，然后重复填充 0 直到再次找到值

Question

我有以下数据框:

miniDF1 <- data.frame(Pred = c("A","A","B","A","B","B","C","A","B","C","A","A","A","A","B","A","C","B"))

    Pred
1     A
2     A
3     B
4     A
5     B
6     B
7     C
8     A
9     B
10    C
11    A
12    A
13    A
14    A
15    B
16    A
17    C
18    B

我正在尝试创建一个用 1 填充的新列，直到在 Pred 中找到“C”，然后用 0 填充新列，直到找到下一个“C”，然后重复这样直到DF结束。我尝试了以下方法:

miniDF1 <- miniDF1 %>%
  mutate(Outcome = ifelse(str_detect(Pred, "C"), 1, 0)) %>% 
  fill(Outcome, .direction = 'up')

     Pred Outcome
1     A       0
2     A       0
3     B       0
4     A       0
5     B       0
6     B       0
7     C       1
8     A       0
9     B       0
10    C       1
11    A       0
12    A       0
13    A       0
14    A       0
15    B       0
16    A       0
17    C       1
18    B       0

但这只是将 1 放在有“C”所在的同一行中。

这是预期的样子:

miniDF2 <- data.frame(Pred = c("A","A","B","A","B","B","C","A","B","C","A","A","A","A","B","A","C","B"),
                     Outcome = c(1,1,1,1,1,1,1,0,0,0,1,1,1,1,1,1,1,0))

     Pred Outcome
1     A       1
2     A       1
3     B       1
4     A       1
5     B       1
6     B       1
7     C       1
8     A       0
9     B       0
10    C       0
11    A       1
12    A       1
13    A       1
14    A       1
15    B       1
16    A       1
17    C       1
18    B       0

我不知道如何让值相应地翻转，但我认为这就是我的代码的 fill(Outcome, .direction = 'up') 部分的目的做。

Answer 1

miniDF1$Outcome <- cumsum(c(1, head(miniDF1$Pred == 'C', -1))) %% 2

miniDF1
   Pred Outcome
1     A       1
2     A       1
3     B       1
4     A       1
5     B       1
6     B       1
7     C       1
8     A       0
9     B       0
10    C       0
11    A       1
12    A       1
13    A       1
14    A       1
15    B       1
16    A       1
17    C       1
18    B       0

在 tidyverse:

library(dplyr)
miniDF1 %>%
  mutate(Outcome = cumsum(lag(Pred == 'C', default = TRUE)) %% 2)