根据 R 中的第二列创建新行值

Question

我想创建一个名为“X”的新变量，它是“B”和“D”的总和

type <- c( "A", "B","C","D","E")
cnt <- c(2,5,3,7,8)

df <- data.frame(type,cnt)

> df
  type cnt
1    A   2
2    B   5
3    C   3
4    D   7
5    E   8

期望的输出是

> df
  type cnt
1    A   2
2    B   5
3    C   3
4    D   7
5    E   8
6    X  12

如果我们添加另一个分组变量（例如日期），如何扩展它？想要每天添加 X

 date <- c("2022-01-01","2022-01-01","2022-01-01","2022-01-01","2022-01-01","2022-01-02","2022-01-02","2022-01-02","2022-01-02","2022-01-02")
type <- c("A", "B","C","D","E","A", "B","C","D","E")
cnt <- c(2,5,3,7,8, 1,9,8,2,5)

df <- data.frame(date,type,cnt)

df
         date type cnt
1  2022-01-01    A   2
2  2022-01-01    B   5
3  2022-01-01    C   3
4  2022-01-01    D   7
5  2022-01-01    E   8
6  2022-01-02    A   1
7  2022-01-02    B   9
8  2022-01-02    C   8
9  2022-01-02    D   2
10 2022-01-02    E   5

期望的输出是

df
         date type cnt
1  2022-01-01    A   2
2  2022-01-01    B   5
3  2022-01-01    C   3
4  2022-01-01    D   7
5  2022-01-01    E   8
6  2022-01-01    X  12
7  2022-01-02    A   1
8  2022-01-02    B   9
9  2022-01-02    C   8
10 2022-01-02    D   2
11 2022-01-02    E   5
12 2022-01-02    X   11

Answer 1

您还可以使用：

df %>%
  add_row(type= 'X', cnt = sum(.$cnt[.$type %in% c('B', 'D')]))

  type cnt
1    A   2
2    B   5
3    C   3
4    D   7
5    E   8
6    X  12

更新：

df %>%
   group_by(date)%>%
   group_modify(~add_row(.,type = 'X', 
                           cnt = sum(.$cnt[.$type%in%c('B', 'D')])))
# A tibble: 12 x 3
# Groups:   date [2]
   date       type    cnt
   <chr>      <chr> <int>
 1 2022-01-01 A         2
 2 2022-01-01 B         5
 3 2022-01-01 C         3
 4 2022-01-01 D         7
 5 2022-01-01 E         8
 6 2022-01-01 X        12
 7 2022-01-02 A         1
 8 2022-01-02 B         9
 9 2022-01-02 C         8
10 2022-01-02 D         2
11 2022-01-02 E         5
12 2022-01-02 X        11