R—在R中通过省略号传递列名

我们可以把元素转换成 ... !!! )

myFunction <- function(dat, ...){
    columns <- quos(...) # convert to quosures

 dat %>% 
     group_by(!!! columns) %>% # evaluate 
     summarise(mean = mean(wt))

 }

myFunction(df, race, gender)
# A tibble: 2 x 3
# Groups:   race [?]
#   race gender  mean
#  <int>  <int> <dbl>
#1     1      1    75
#2     2      2    76

myFunction(df, race)
# A tibble: 2 x 2
#   race  mean
#  <int> <dbl>
#1     1    75
#2     2    76

如果它改变了它,就会看到不同

df <- data.frame(id = 1:10, wt = 71:80, gender = rep(1:2, 5), 
      race = rep(1:2, each = 5))

myFunction(df, race, gender)
myFunction(df, race)
myFunction(df, gender)

如果我们决定将参数作为带引号的字符串传递,那么我们可以利用 group_by_at

myFunction2 <- function(df, ...) {
 columns <- c(...)
 df %>% 
   group_by_at(columns) %>%
   summarise(mean= mean(wt))

 }

myFunction2(df, "race", "gender")