使用 dplyr 编程的问题——列，这绝对是一个被拾取为公式的向量

Question

我正在编写一个函数来使用 highcharter 重现几个具有相似格式（和其他内容）的图表。如果名称更改或者我想做一些不同的事情，我希望能够 select 数据集的不同列，并且我接受这些参数 {{ }}.但是后来我得到了这个奇怪的错误：

Error: Problem with `mutate()` input `x`.
x Input `x` must be a vector, not a `formula` object.
i Input `x` is `~Year`.

这是我的（最小可重现的）代码：

library(dplyr)
library(highcharter)

plot_high_chart <- function(.data,
                            chart_type = "column",
                            x_value = Year,
                            y_value = total,
                            group_value = service) {
  .data %>% 
  hchart(chart_type, hcaes(x = {{x_value}}, y = {{y_value}}, group = {{group_value}}))
}

data %>% plot_high_chart()

这是数据的 dput 结果：

structure(list(Year = c(2016, 2017, 2017, 2018, 2018, 2018), 
    service = structure(c(10L, 3L, 9L, 5L, 7L, 9L), .Label = c("Defense Logistics Agency", 
    "Chemical and Biological Defense Program", "Defense Information Systems Agency", 
    "United States Special Operations Command", "Office of the Secretary Of Defense", 
    "Missile Defense Agency", "Defense Advanced Research Projects Agency", 
    "Navy", "Army", "Air Force"), class = "factor"), total = c(9.435, 
    0, 10.442, 9.969, 73.759, 8.855)), row.names = c(NA, -6L), groups = structure(list(
    Year = c(2016, 2017, 2018), .rows = structure(list(1L, 2:3, 
        4:6), ptype = integer(0), class = c("vctrs_list_of", 
    "vctrs_vctr", "list"))), row.names = c(NA, 3L), class = c("tbl_df", 
"tbl", "data.frame"), .drop = TRUE), class = c("grouped_df", 
"tbl_df", "tbl", "data.frame"))

Answer 1

{{a}} 是 shorthand for !!enquo(a)，它捕获提供给 a 的表达式以及应计算此表达式的上下文。在您的情况下，上下文是数据框，它已经提供给函数。因此，这里使用的更好的 rlang 动词是 ensym(a)，它捕获提供给 a 的符号名称：

plot_high_chart <- function(.data,
                            chart_type = "column",
                            x_value = "Year",             # <-- Note: strings
                            y_value = "total",            
                            group_value = "service") {
  .data %>%
      hchart(chart_type, hcaes(x = !!rlang::ensym(x_value),    # <- ensym instead of {{
                               y = !!rlang::ensym(y_value),
                               group = !!rlang::ensym(group_value)))
}

作为奖励，该函数现在可以处理符号和字符串：

data %>%
   plot_high_chart(x_value= "Year", y_value= "total", group_value= "service")    # Works
data %>% 
   plot_high_chart(x_value= Year, y_value= total, group_value= service)     # Also Works

使用 dplyr 编程的问题——列，这绝对是一个被拾取为公式的向量

Problem programming with dplyr--column which is definitely a vector being picked up as a formula

r

dplyr

r-highcharter

tidyeval

rlang