R ggplot2：在平铺图中对离散类中的连续数据进行分类

Question

我有一个填充的 ggplot 等高线图，在 100x100 网格上描绘了连续的 R 平方值。默认情况下，图例以类似梯度的连续方式描述值，这是由于数据的连续性造成的。

然而，我想按类别对数据进行分类和可视化，每个类别涵盖 0.05 R 平方值的范围（即类别 1 = 0.00-0.05，类别 2 = 0.05-0.10 等）。我尝试了几个命令，例如 scale_fill_brewer 和 scale_fill_gradient2。后者实际上确实生成了某种离散类，但类标签描述了中断值而不是类范围。 Scale_fill_brewer 返回将连续数据强制转换为离散比例的错误，这是有道理的，尽管我不知道如何解决它。

为了让事情变得更复杂，我更喜欢使用多样化的调色板来更容易地识别特定的类。此外，我有许多具有不同最大 R 平方值的不同等高线图。所以理想情况下，代码是通用的，也可以很容易地用于其他绘图。

到目前为止，这是我拥有的代码：

library(scales)
library(ggplot2)
p1 <- ggplot(res, aes(x=Var1, y=Var2, fill=R2)) +
  geom_tile
p1 +
 theme(axis.text.x=element_text(angle=+90)) +
 geom_vline(xintercept=c(seq(from = 1, to = 101, by = 5)),color="#8C8C8C") +
 geom_hline(yintercept=c(seq(from = 1, to = 101, by = 5)),color="#8C8C8C") +
 labs(list(title = "Contour plot of R^2 values for all possible correlations between Simple Ratio indices & Nitrogen Content", x = "Wavelength 1 (nm)", y = "Wavelength 2 (nm)")) +
 scale_x_discrete(breaks = c("b450","b475","b500","b525","b550","b575","b600","b625","b650","b675","b700","b725","b750","b775","b800","b825","b850","b875","b900","b925","b950")) +
 scale_y_discrete(breaks = c("b450","b475","b500","b525","b550","b575","b600","b625","b650","b675","b700","b725","b750","b775","b800","b825","b850","b875","b900","b925","b950")) +
 scale_fill_continuous(breaks = c(seq(from = 0, to = 0.7, by = 0.05)), low = "black", high = "green")

此时的输出如下所示：

Answer 1

您可能会使用什么 scale_fill_gradientn() 未经测试，因为您未能提供可重现的示例

library(scales)
library(ggplot2)
ggplot(res, aes(x=Var1, y=Var2, fill=R2)) +
  geom_tile() + 
  scale_fill_gradientn(
      colours = terrain.colors(15), 
      breaks = seq(from = 0, to = 0.7, by = 0.05)
  )