R 组合预定义美学(Ggplot2)

您可以使用一些rlang魔法来操作贴图. 简而言之，我们只是指定新的美学，如果它是不正确的，否则我们创建一个结合这两个表达的新调用.

library(ggplot2)
library(rlang)

combine_mapping <- function(user, fixed, fun = interaction) {
  names(user)  <- standardise_aes_names(names(user))
  names(fixed) <- standardise_aes_names(names(fixed))
  fun <- enexpr(fun)
  for (var in names(fixed)) {
    inject <- quo_get_expr(fixed[[var]])
    if (var %in% names(user)) {
      expr <- quo_get_expr(user[[var]])
      user[[var]] <- call2(fun, !!!list(inject, expr))
    } else {
      user[[var]] <- fixed[[var]]
    }
  }
  user
}

一些演示

user_mapping <- aes(mpg, disp, colour = cyl)

# Case of missing aesthetic
combine_mapping(aes(mpg, disp), aes(colour = cyl))
#> Aesthetic mapping: 
#> * `x`      -> `mpg`
#> * `y`      -> `disp`
#> * `colour` -> `cyl`

# Combining aesthetic
combine_mapping(user_mapping, aes(colour = gear))
#> Aesthetic mapping: 
#> * `x`      -> `mpg`
#> * `y`      -> `disp`
#> * `colour` -> `interaction(gear, cyl)`

# Multiple aesthetics
combine_mapping(user_mapping, aes(colour = gear, x = cty))
#> Aesthetic mapping: 
#> * `x`      -> `interaction(cty, mpg)`
#> * `y`      -> `disp`
#> * `colour` -> `interaction(gear, cyl)`

# Other function to combine
combine_mapping(user_mapping, aes(colour = gear), fun = paste0)
#> Aesthetic mapping: 
#> * `x`      -> `mpg`
#> * `y`      -> `disp`
#> * `colour` -> `paste0(gear, cyl)`

# Works in plot
ggplot(mtcars, combine_mapping(aes(mpg, disp, colour = cyl), aes(colour = gear))) +
  geom_point()

^{创建于2023-12-22，共reprex v2.0.2个}