r - 使用 ggplot2 包在颜色条上手动添加标签名称

Question

我想通过为比例尺底部和顶部的值添加手动标签名称(低和高)来更改连续颜色图例。我怎样才能做到这一点？

x <- 1:100
y <- runif(100) * 100
tib <- tibble(x, y)

ggplot(tib, aes(x = x, y = y, color = y)) +
  geom_point() +
  binned_scale(aesthetics = "color",
               scale_name = "stepsn", 
               palette = function(x) c("red", "yellow", "green", "yellow", "red"),
               breaks = c(5, 10, 25, 60),
               limits = c(0, 100),
               show.limits = TRUE, 
               guide = "colorsteps")

预期输出:

我尝试在脚本中添加 labels = c("Low", 5, 10, 25, 60, "High") 但显示此错误:

Error in f():
! Breaks and labels are different lengths
Run rlang::last_error() to see where the error occurred.

Answer 1

实现此目的的一个简单选择(我刚刚发现)是将命名向量传递给 limits 参数，其中名称是您想要的标签:

set.seed(123)

library(ggplot2)

ggplot(tib, aes(x = x, y = y, color = y)) +
  geom_point() +
  binned_scale(aesthetics = "color",
               scale_name = "stepsn", 
               palette = function(x) c("red", "yellow", "green", "yellow", "red"),
               breaks = c(5, 10, 25, 60),
               limits = c(low = 0, high = 100),
               show.limits = TRUE, 
               guide = "colorsteps")

编辑对箭头不是100%确定，但添加一些箭头的一个简单选择是在标签中包含左箭头的UTF-8符号:

set.seed(123)
x <- 1:100
y <- runif(100) * 100
tib <- data.frame(x, y)

library(ggplot2)

ggplot(tib, aes(x = x, y = y, color = y)) +
  geom_point() +
  binned_scale(aesthetics = "color",
               scale_name = "stepsn", 
               palette = function(x) c("red", "yellow", "green", "yellow", "red"),
               breaks = c(5, 10, 25, 60),
               limits = c("\u2190 low" = 0, "\u2190 high" = 100),
               show.limits = TRUE, 
               guide = "colorsteps")