scale_size_continuous() 的自定义颜色

Question

在下图中，如何以绿色显示所有 cty >= 30 值，以红色显示 cty < 30 值？谢谢！

library(ggplot2)
data(mpg)
p <- ggplot() +
    geom_point(data = mpg, aes(displ, manufacturer, size = cty), alpha = 0.2) +
    scale_size_continuous(breaks = c(30, 20, 10)) +
    scale_color_manual(values = c("green", "red", "red"))  # does not work
p

Answer 1

我不认为数据集中有任何 cty 值大于 30，但由于这只是一个示例，让我们将截止值设置为 15：

ggplot() +
    geom_point(data = mpg, aes(displ, manufacturer, size = cty, 
                               color = cty <= 15), alpha = 0.2) +
    scale_size_continuous(breaks = c(30, 20, 10)) +
    scale_color_manual(values = c("green", "red"))

如果你想合并图例，你需要一个模拟离散色标的连续色标，比如：

ggplot() +
    geom_point(data = mpg, aes(displ, manufacturer, size = cty, 
                               color = cty), alpha = 0.2) +
    scale_size_continuous(breaks = c(30, 20, 10)) +
    scale_color_gradientn(colors = c("red", 'red', "green", 'green'),
                          values = c(0, 0.5, 0.50001, 1),
                          breaks = c(30, 20, 10),
                         guide = guide_legend())

scale_size_continuous() 的自定义颜色

Custom color for scale_size_continuous()

r

ggplot2