Expss标签是否可以通过ggplot标题访问？

Question

我希望从Expss变量标签向ggplot添加标题。 Expss package使用变量标签和值标签（带有基础数字）创建新的数据类型。有什么方法可以通过引用变量名称并将其作为标题包含在ggplot中来访问分配的变量标签？同样，Expss表标题可以来自变量标签吗？

Answer 1

通常来说，您可以使用var_lab函数：var_lab(my_dataframe$my_variable)轻松获得变量标签。在下面的示例中，您可以看到它如何与表格标题和ggplot一起使用：

library(ggplot2)
library(expss)
data(mtcars)
mtcars = apply_labels(mtcars,
                      mpg = "Miles/(US) gallon",
                      cyl = "Number of cylinders",
                      disp = "Displacement (cu.in.)",
                      hp = "Gross horsepower",
                      drat = "Rear axle ratio",
                      wt = "Weight (1000 lbs)",
                      qsec = "1/4 mile time",
                      vs = "Engine",
                      vs = c("V-engine" = 0,
                             "Straight engine" = 1),
                      am = "Transmission",
                      am = c("Automatic" = 0,
                             "Manual"=1),
                      gear = "Number of forward gears",
                      carb = "Number of carburetors"
)

# table with caption from label
cro_cpct(mtcars$am, mtcars$vs) %>% set_caption(var_lab(mtcars$am))

# ggplot with title from label
use_labels(mtcars, {
    # '..data' is shortcut for all 'mtcars' data.frame inside expression 
    ggplot(..data) +
        geom_point(aes(y = mpg, x = wt, color = qsec)) +
        facet_grid(am ~ vs) +
        ggtitle(var_lab(mpg))
})