r - 如何避免省略号......在dplyr中？

Question

我想创建一个接受分组参数的函数。其中可以是单个或多个变量。我希望它看起来像这样:

wanted <- function(data, groups, other_params){
  data %>% group_by( {{groups}} ) %>% count()
}

这仅在给出单个组时有效，但在有多个组时会中断。我知道可以使用带有省略号的以下内容 ... (但我想要语法 groups = something ):

not_wanted <- function(data, ..., other_params){
  data %>% group_by( ... ) %>% count()
}

这是整个代码:

library(dplyr)
library(magrittr)

iris$group2 <- rep(1:5, 30)

wanted <- function(data, groups, other_params){
  data %>% group_by( {{groups}} ) %>% count()
}

not_wanted <- function(data, ..., other_params){
  data %>% group_by( ... ) %>% count()
}

# works
wanted(iris, groups = Species )
not_wanted(iris, Species, group2)

# doesn't work
wanted(iris, groups = vars(Species, group2) )
wanted(iris, groups = c(Species, group2) )
wanted(iris, groups = vars("Species", "group2") )
#  Error: Column `vars(Species, group2)` must be length 150 (the number of rows) or one, not 2

Answer 1

你们把事情复杂化了，这很好用:

library(tidyverse)

wanted <- function(data, groups){
  data %>%  count(!!!groups)
}

mtcars %>% wanted(groups = vars(mpg,disp,hp))

# A tibble: 31 x 4
     mpg  disp    hp     n
   <dbl> <dbl> <dbl> <int>
 1  10.4  460    215     1
 2  10.4  472    205     1
 3  13.3  350    245     1
 4  14.3  360    245     1
 5  14.7  440    230     1
 6  15    301    335     1
 7  15.2  276.   180     1
 8  15.2  304    150     1
 9  15.5  318    150     1
10  15.8  351    264     1
# … with 21 more rows