r - 使ggplot aes颜色映射以逻辑语句为条件

Question

我想让 ggplot 中的颜色映射以逻辑测试的结果为条件。因此，例如，我可以提供一个输入，然后将颜色 aes 设置为 a、b 或 c。但是，我似乎无法让它工作，因为我能设法做到这一点的唯一方法是传递类似“a”的东西，当然它实际上不会映射到数据中的 a 列。任何帮助将不胜感激!

test.data <- tibble(nums = seq(1:6),
                    a = c("a","a","a", "b", "b", "b"),
                    b = c("a","a", "b", "b", "a","a"),
                    c = c("a", "b", "a", "b", "a", "b"))

ggplot(data = data) +
  geom_point(aes(x = nums, y = nums, color = a))

color.choice <- "a"

ggplot(data = data) +
  geom_point(aes(x = nums, y = nums, color = color.choice))

Answer 1

这可以通过例如.data 代名词，它允许您选择作为字符串传递的列:

library(ggplot2)

test.data <- data.frame(nums = seq(1:6),
                    a = c("a","a","a", "b", "b", "b"),
                    b = c("a","a", "b", "b", "a","a"),
                    c = c("a", "b", "a", "b", "a", "b"))

color.choice <- "a"

ggplot(data = test.data) +
  geom_point(aes(x = nums, y = nums, color = .data[[color.choice]]))