r - ggplot:渐变填充高点和低点

样本数据：

set.seed(123)
dtf <- as.data.frame(rnorm(n = 1000, mean = 0, sd = 0.02))
dtf = as.data.frame(dtf)
dtf = cbind(Obs = rownames(dtf), dtf)
names(dtf)[2] = "random"
head(dtf)

  Obs       random
1   1 -0.011209513
2   2 -0.004603550
3   3  0.031174166
4   4  0.001410168
5   5  0.002585755
6   6  0.034301300

简单点图：

gp = ggplot() +
  geom_point(data = dtf, aes(x = Obs, y = random))

gp

我想用darkgreen填充高点，而用darkred填充低点。以下内容不起作用：

gp = ggplot() +
  geom_point(data = dtf, aes(x = Obs, y = random)) +
  scale_colour_gradient(low = "darkgreen", mid = "blue", high = "darkred")

gp

有什么建议吗？

最佳答案

您正在构造错误的ggplot呼叫。通话不起作用的原因是，您没有将颜色映射（通过aes()映射到任何变量）。尝试

ggplot(dtf, aes(x = Obs, y = random, color = random)) +
  geom_point() +
  scale_colour_gradient2(low = "darkgreen", mid = "blue", high = "darkred")