以编程方式使用dplyr case_w [英] use dplyr case_when programmatically

问题描述

我正在尝试使用dplyr case_when并传递变量，但结果不符合预期。

I'm trying to use dplyr case_when and pass variable but the result was not as expected.

示例：

library(dplyr)
mtcars %>% 
  mutate(cg = case_when(carb <= 2 ~ "low",
                        carb > 2  ~ "high")) ---this works

但是，当我尝试传递变量时，它将全部返回为低

However, when I try to pass a variable, it returns all as "low"

var <- quo(carb)
mtcars %>% 
  mutate(cg = case_when(!!var <= 2 ~ "low",
                    !!var > 2  ~ "high"))

推荐答案

这是一个操作顺序问题，您需要使用方括号：

This is an order of operations problem, you need to use brackets:

quo_function <- function(df, var) {
  df %>%
    mutate(cg = case_when((!!var) <= 2 ~ "low",
                          (!!var) > 2 ~ "high"))  
}

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