如何在 r 中使用胶水在绘图的标题/副标题中使用变量的最大值？

Question

我有一个用户定义的函数，可以计算给定国家/地区的每日新冠病例并给出一个数据框：

fn_daily_cases <- function(Country_Name = India)
  {
  Country_Name <- rlang::quo_name(rlang::enquo(Country_Name))
  # above line will insert quote to the value in variable Country_Name
  
  df_gather %>% filter(Country.Region == Country_Name) %>% 
    mutate(daily_cases = abs(Cases_Count - lag(Cases_Count, default = 0))) %>% 
    # at beginning it will give 0 instead of NA
    
    arrange(desc(Date))
  
  } 

fn_daily_cases(Spain)

####### output ########

Country.Region Date   Cases_Count daily_cases
<chr>          <date> <int>       <dbl>

Spain   2020-12-11  1730575 10519   
Spain   2020-12-10  1720056 7955    
Spain   2020-12-09  1712101 9773    
Spain   2020-12-08  1702328 0   
Spain   2020-12-07  1702328 17681   
Spain   2020-12-06  1684647 0   
Spain   2020-12-05  1684647 0   
Spain   2020-12-04  1684647 8745    
Spain   2020-12-03  1675902 10127   
Spain   2020-12-02  1665775 9331    

问题：当我尝试使用另一个函数绘制此数据框时，我无法在 subtitle

中显示 max( Cases_Count)

library(glue)
library(tidyverse)

fn_daily_cases_plot <- function(country_selected = India) {
  
  fn_daily_cases({{country_selected}}) %>% 
  ggplot(aes(Date, y = daily_cases)) +
  geom_line(col = "midnightblue") +
  labs(title = glue("{quo_name(enquo(country_selected))} Daily Cases") ,
       subtitle = glue("Total cases so far: {max(Cases_Count)}" )
       ) +
  theme_light()
}

fn_daily_cases_plot(Spain)


##### output ######

Error in eval(parse(text = text, keep.source = FALSE), envir) : object 'Cases_Count' not found

Answer 1

尝试先将数据保存在单独的tibblex，然后调用 max(x$Cases_Count).

fn_daily_cases_plot <- function(country_selected = India) {

  x <- fn_daily_cases({{country_selected}})

  ggplot(x, aes(Date, y = daily_cases)) + 
  geom_line(col = "midnightblue") +
  labs(title = glue("{quo_name(enquo(country_selected))} Daily Cases") , 
        subtitle = glue("Total cases so far: {max(x$Cases_Count)}" )) +
  theme_light() 
}

无论如何，我不知道您为什么更喜欢 glue 而不是基本替代品 paste （另见this question）。