枚举枚举中的分组变量

Question

我想知道如何使用row_number或其他方法将变量组转换为整数

tibble_test <- tibble(A = letters[1:10], group = c("A", "A", "A", "B", "B", "C", "C", "C", "C", "D"))

# to get the enumeration inside each group of 'group'
tibble_test %>% 
  group_by(group) %>% 
  mutate(G1 = row_number())

但是我想得到这个输出：

# A tibble: 10 x 4
   A     group    G1    G2
   <chr> <chr> <dbl> <dbl>
 1 a     A         1     1
 2 b     A         2     1
 3 c     A         3     1
 4 d     B         1     2
 5 e     B         2     2
 6 f     C         1     3
 7 g     C         2     3
 8 h     C         3     3
 9 i     C         4     3
10 j     D         1     4

[我的问题是：如何获得G2列，我知道我可以将'group'var转换为一个因子然后为整数（在排列小数之后），但是我想知道是否可以使用计数来完成。

Answer 1

您只需要再执行一步，并在group_indices()中包含组索引。请注意，您的数据如何安排/排序将影响索引。

library(dplyr)

tibble_test <- tibble(A = letters[1:10], group = c("A", "A", "A", "B", "B", "C", "C", "C", "C", "D"))

# to get the enumeration inside each group of 'group'
tibble_test %>% 
  group_by(group) %>% 
  mutate(G1 = row_number(),
         G2 = group_indices())

# A tibble: 10 x 4
# Groups:   group [4]
   A     group    G1    G2
   <chr> <chr> <int> <int>
 1 a     A         1     1
 2 b     A         2     1
 3 c     A         3     1
 4 d     B         1     2
 5 e     B         2     2
 6 f     C         1     3
 7 g     C         2     3
 8 h     C         3     3
 9 i     C         4     3
10 j     D         1     4