如何在 R 函数中创建一个我可以在函数中使用的新对象

Question

我正在尝试编写一个函数来创建一个 ggplot，其组件全部基于单个输入。我有一个数据框，包含种族、三项评估（阅读、写作、数学）的结果以及每个结果的置信区间。我想创建一个函数，该函数将根据读取、写入或数学创建相同的绘图。

例如，如果我使用 var Read_perc

library(tidyverse)
dat <- data.frame (Race = c("White", "Black", "Inidigenous"),
                  Read_perc = c (0.756, 0.592, 0.548),
                  Read_low_ci = c (0.742, 0.498, 0.467),
                  Read_high_ci = c(0.769, 0.679, 0.628),
                  Write_perc = c (0.717, 0.625, 0.497),
                  Write_low_ci = c (0.703, 0.532, 0.416),
                  Write_high_ci = c (0.731, 0.710, 0.578))

my_plot_function <- function (df, var){
  var <- enquo(var)
  df %>% 
    ggplot (aes (x = reorder (Race, !! var), y = !! var)) +
    geom_col () +
    coord_flip () +
    geom_text (aes (label = scales::percent(!! var, accuracy = 1)),
               y = 0.05,
               colour = "white")

}

my_plot_function(dat, Read_perc)

但是，我只想使用 Read 或 Write，然后用它来调用不同的列，例如 Read_perc、Read_low_ci 等

例如，这行不通：

my_plot_function <- function (df, var){

var <- enquo (var)
var_low_ci <- paste0 (var, "_low_ci")
var_high_ci <- paste0 (var, "_high_ci")

df %>% 
    ggplot (aes (x = reorder (Race, !! var), y = !! var)) +
    geom_col () +
    coord_flip () +
    geom_text (aes (label = scales::percent(!! var, accuracy = 1)),
               y = 0.05,
               colour = "white") +
       geom_errorbar(aes(ymin = var_low_ci,
                         ymax = var_high_ci),
                         colour = "black")

最终图表应如下所示：

Answer 1

我们可以转换为 symbol 求值

my_plot_function <- function (df, var){

   var <- rlang::as_string(rlang::ensym(var))
   var_low_ci <- rlang::sym(str_c(str_remove(var, "_perc"), "_low_ci"))
   var_high_ci <- rlang::sym(str_c(str_remove(var, "_perc"), "_high_ci"))
    var1 <- rlang::sym(var)

  df %>% 
    ggplot(aes(x = reorder(Race, !! var1), y = !! var1)) +
    geom_col () + 
    coord_flip () +
           geom_text(aes(label = scales::percent(!! var1, accuracy = 1)),
                      y = 0.05,
                      colour = "white") +
              geom_errorbar(aes(ymin = !!var_low_ci,
                                ymax = !!var_high_ci),
                                colour = "black")
}

-测试

my_plot_function(dat, Read_perc)

如何在 R 函数中创建一个我可以在函数中使用的新对象

How do I create a new object in an R function, that I can use within the function

r

tidyeval