R ggplot2 - 调整连续颜色条渐变上的中断之间的距离

Question

我在 ggplot2 中创建了一个热图使用 geom_tile并使用 scale_fill_gradientn 映射值.颜色条被分成两个渐变。一个梯度映射值从 0 到 0.05，另一个梯度映射值从 0.05 到 1。热图看起来像预期的那样，但颜色条不是预期的。我希望红黄色渐变 (0-0.05) 与黑棕色渐变 (0.05-1) 具有相同的高度。

QUESTION: How do I modify the colourbar so the value 0.05 is in the middle/center of the bar making the height of the two distinct color gradients identical?

In other words, imagine that the 0.05 tick mark is a slider and you can move it to the middle of the bar expanding/compressing the respective gradients.

类似的问题已在下面的两篇文章中讨论过，但没有确定的解决方案，或者至少不是我可以轻松理解和回答我的问题的解决方案:

Similar question 1

Similar question 2

非常感谢大家阅读我的问题并思考可能的解决方案。到目前为止，除了在 Photoshop 中编辑颜色栏之外，我想不出任何有用的东西。彼得



可重现的示例:

TEST <- read.csv ("https://filetea.me/n3wHRhuy0GlS4xvjQDxs95BVA",header=T,row.names=NULL)

library(ggplot2) 
ggplot(TEST, aes(x=Measure, y=SMTSD))+
    geom_tile(aes(fill=Pval),colour="grey50", size=0.1) +
    scale_x_discrete(expand = c(0,0))+
    coord_equal(ratio=1)+

scale_fill_gradientn(colours=c("red","yellow","black","#996633"),
    values=c(0,0.0499,0.05,1),
    na.value="white", guide="colourbar",
    name="P-value",limits=c(0,1),breaks=c(0,0.05,1))+

 guides(fill = guide_colourbar(barheight = 20, direction = "vertical",
        title.position="top", title.hjust = 0.5,title.vjust = 0.5, nbin = 50))

Answer 1

更改 scale_fill_gradient 值和中断将为您提供所需的内容:

ggplot(TEST, aes(x=Measure, y=SMTSD))+
  geom_tile(aes(fill=Pval^0.2313782),colour="grey50", size=0.1) +
  scale_x_discrete(expand = c(0,0))+
  coord_equal(ratio=1)+
  scale_fill_gradientn(colours=c("red","yellow","black","#996633"),
                       values=c(0,0.0499,0.05,1)^ 0.2313782,
                       na.value="white", guide="colourbar",
                       name="P-value",limits=c(0,1),breaks=c(0,0.05,1)^ 0.2313782, 
                       labels=c(0,0.05,1))+
  guides(fill = guide_colourbar(barheight = 20, direction = "vertical",
                               title.position="top", title.hjust = 0.5,title.vjust = 0.5, nbin = 50))

附言用新图像编辑