使用tidyeval编写自定义case_when函数以在dplyr mutate中使用 [英] Writing a custom case_when function to use in dplyr mutate using tidyeval

问题描述

我正在尝试编写自定义case_when函数以在dplyr中使用.我一直在阅读其他问题中张贴的tidyeval示例，但仍然不知道如何使其工作.这里是一个代表:

I'm trying to write a custom case_when function to use inside dplyr. I've been reading through the tidyeval examples posted in other questions, but still can't figure out how to make it work. Here's a reprex:

df1 <- data.frame(animal_1 = c("Horse", "Pig", "Chicken", "Cow", "Sheep"),
           animal_2 = c(NA, NA, "Horse", "Sheep", "Chicken"))


translate_title <- function(data, input_col, output_col) {
  mutate(data, 
    !!output_col := case_when(
    input_col == "Horse" ~ "Cheval",
    input_col == "Pig" ~ "Рorc",
    input_col == "Chicken" ~ "Poulet",
    TRUE ~ NA)
  )
}


df1 %>% 
  translate_title("animal_1", "animaux_1") %>% 
  translate_title("animal_2", "animaux_2")

当我尝试运行此命令时， mutate_impl(.data，点)中的错误:评估错误:必须为字符串类型，而不是逻辑类型.

When I try to run this, I'm getting Error in mutate_impl(.data, dots) : Evaluation error: must be type string, not logical.

我实际上还想重写该函数，以便可以像这样使用它:

Also I would actually like to rewrite the function so that it can be used like this:

df1 %>% 
  mutate(animaux_1 = translate_title(animal_1),
         animaux_2 = translate_title(animal_2)
         )

但不确定如何.

推荐答案

根据您想如何将输入传递给函数，可以通过两种方式解决它:

Depending on how you want to pass your input to the function you can solve it in two ways :

1)使用 {{}}

library(dplyr)

translate_title <- function(data, input_col, output_col) {

   mutate(data, 
        !!output_col := case_when(
        {{input_col}} == "Horse" ~ "Cheval",
        {{input_col}} == "Pig" ~ "Рorc",
        {{input_col}} == "Chicken" ~ "Poulet",
        TRUE ~ NA_character_)
  )
}

df1 %>% 
  translate_title(animal_1, "animaux_1") %>%
  translate_title(animal_2, "animaux_2")

#  animal_1 animal_2 animaux_1 animaux_2
#1    Horse     <NA>    Cheval      <NA>
#2      Pig     <NA>      Рorc      <NA>
#3  Chicken    Horse    Poulet    Cheval
#4      Cow    Sheep      <NA>      <NA>
#5    Sheep  Chicken      <NA>    Poulet

2)传递使用 sym 和 !!

translate_title <- function(data, input_col, output_col) {
   mutate(data, 
         !!output_col := case_when(
          !!sym(input_col) == "Horse" ~ "Cheval",
          !!sym(input_col) == "Pig" ~ "Рorc",
          !!sym(input_col) == "Chicken" ~ "Poulet",
          TRUE ~ NA_character_)
  )
}

df1 %>% 
  translate_title("animal_1", "animaux_1") %>%
  translate_title("animal_2", "animaux_2")

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