r - 从ggplot2中提取颜色信息？

Question

使用保存在名为foo.txt的文件中的虚拟代码...

COG,station1,station2,station3,station4,station5
COG000Z,0.019393497,0.183122497,0.089911227,0.283250444,0.074110521
COG0002,0.044632051,0.019118032,0.034625785,0.069892277,0.034073709
COG0001,0.033066112,0,0,0,0
COG0004,0.115086472,0.098805295,0.148167492,0.040019101,0.043982814
COG0005,0.064613057,0.03924007,0.105262559,0.076839235,0.031070155
COG0006,0.079920475,0.188586049,0.123607421,0.27101229,0.274806929
COG0007,0.051727492,0.066311584,0.080655401,0.027024185,0.059156417
COG0008,0.126254841,0.108478559,0.139106704,0.056430812,0.099823028

我在 ggplot2 中制作了一张热图，并在 stackexchange 上遵循此答案并附带代码。

> library(ggplot2)
> foo = read.table('foo.txt', header=T, sep=',')
> foomelt = melt(foo)
Using COG as id variables
> ggplot(foomelt, aes(x=COG, y=variable, fill=value)) + geom_tile() + scale_fill_gradient(low='white', high='steelblue')

它产生了一个非常好的热图，但我真的只是在每个图块的颜色代码之后（基本上是原始的 foo 但用颜色代码代替每个变量）。知道该怎么做吗？

Answer 1

我正在努力将所有与比例尺相关的代码从 ggplot2 拉到一个单独的包中——这将使以不同方式使用相同比例尺变得更加容易。有关正在进行的代码，请参阅https://github.com/hadley/scales 。

Answer 2

而不是从图中提取颜色，使用colorRampPalette：

a<-colorRampPalette(c("white","steelblue"))
plot_colours<-a(n)

n热图中的颜色数量在哪里。在你的例子中，我得到n=6了：

n<-6
a(n)

返回

[1] "#FFFFFF" "#DAE6F0" "#B4CDE1" "#90B3D2" "#6A9BC3" "#4682B4"

和

image(1:n,1,as.matrix(1:n),col=a(n))

返回