R group_by在循环中使用不同的列名

Question

student <- data.frame(ID = c(11, 12, 13),
                      Name = c("Devin", "Edward", "Wenli"),
                      Gender = c("M", "M", "F"),
                      Birthdate = c("1984-12-29", "1983-5-6", "1986-8-8"))

selection <- c("Name", "Gender", "Birthdate")

现在我想编写一个循环

library(dplyr)
for(choice in selection){
   df = group_by(choice)
   print(df)
}

但是它不起作用。我该怎么办？

Answer 1

也许这就是你所追求的？

library(dplyr)
for(choice in selection){
  student %>% group_by(!!choice ) %>% print()
}

# A tibble: 3 x 5
# Groups:   "Name" [1]
     ID Name   Gender Birthdate  `"Name"`
  <dbl> <fct>  <fct>  <fct>      <chr>   
1  11.0 Devin  M      1984-12-29 Name    
2  12.0 Edward M      1983-5-6   Name    
3  13.0 Wenli  F      1986-8-8   Name    
# A tibble: 3 x 5
# Groups:   "Gender" [1]
     ID Name   Gender Birthdate  `"Gender"`
  <dbl> <fct>  <fct>  <fct>      <chr>     
1  11.0 Devin  M      1984-12-29 Gender    
2  12.0 Edward M      1983-5-6   Gender    
3  13.0 Wenli  F      1986-8-8   Gender    
# A tibble: 3 x 5
# Groups:   "Birthdate" [1]
     ID Name   Gender Birthdate  `"Birthdate"`
  <dbl> <fct>  <fct>  <fct>      <chr>        
1  11.0 Devin  M      1984-12-29 Birthdate    
2  12.0 Edward M      1983-5-6   Birthdate    
3  13.0 Wenli  F      1986-8-8   Birthdate

请注意，OP仅请求group_by()，而不是summarize()。

!!运算符的解释

Programming with dplyr上的小插图说：

  

在dplyr中（通常在tidyeval中）使用!!说你想要   取消引用的引用，以便对其进行评估，而不引用。