我有一个包含三个标识符的数据集。假设一个识别国家，另一个识别时间，另一个识别人。就像下面的数据框:

   country person time
1        A   John    1
2        A   John    2
3        A   John    3
4        A  Peter    1
5        A  Peter    2
6        A  Peter    3
7        B  David    1
8        B  Thomas   2
9        B  David    3
10       B  Adam     1
11       B  Adam     2
12       B  Thomas   3

我如何创建一个变量来生成一系列字母，这些字母将按国家/地区识别每个人？输出应如下所示:

        country person time   Letterseq
    1        A   John    1    A
    2        A   John    2    A
    3        A   John    3    A
    4        A  Peter    1    B
    5        A  Peter    2    B
    6        A  Peter    3    B
    7        B  David    1    A
    8        B  Thomas   2    B
    9        B  David    3    A
    10       B  Adam     1    C
    11       B  Adam     2    C
    12       B  Thomas   3    B

如果您需要更多说明，请告诉我。

最佳答案

如果每个“国家”的唯一人员长度小于 26，则按“国家”分组，通过将“人员”与 unique匹配来获取数字索引'person' 的值，使用索引从内置向量 'LETTERS' 返回相应的值

library(dplyr)
df1 <- df1 %>%
   group_by(country) %>% 
   mutate(Letterseq = LETTERS[match(person, unique(person))]) %>% 
   ungroup

-输出

df1
# A tibble: 12 × 4
   country person  time Letterseq
   <chr>   <chr>  <int> <chr>    
 1 A       John       1 A        
 2 A       John       2 A        
 3 A       John       3 A        
 4 A       Peter      1 B        
 5 A       Peter      2 B        
 6 A       Peter      3 B        
 7 B       David      1 A        
 8 B       Thomas     2 B        
 9 B       David      3 A        
10 B       Adam       1 C        
11 B       Adam       2 C        
12 B       Thomas     3 B      

数据

df1 <- structure(list(country = c("A", "A", "A", "A", "A", "A", "B", 
"B", "B", "B", "B", "B"), person = c("John", "John", "John", 
"Peter", "Peter", "Peter", "David", "Thomas", "David", "Adam", 
"Adam", "Thomas"), time = c(1L, 2L, 3L, 1L, 2L, 3L, 1L, 2L, 3L, 
1L, 2L, 3L)), class = "data.frame", row.names = c("1", "2", "3", 
"4", "5", "6", "7", "8", "9", "10", "11", "12"))

https://stackoverflow.com/questions/74102204/