从ggplot2中提取颜色信息？

Question

使用保存在一个名为foo.txt的文件这个虚设码...

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 

我在做GGPLOT2热图与following this answer on stackexchange附带的代码。

> 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') 

它产生一个非常好的热图，但我只是每瓦的颜色代码后（基本上是原来的FOO但在地方各变量的颜色代码），我真的。任何想法如何去解决这个问题？

Answer 1

不是从情节中提取的颜色相反，使用colorRampPalette：

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

其中n是在你的热图的颜色数。在你的榜样，我得到n=6这样：

n<-6 
a(n) 

回报

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

和

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

回报

Answer 2

我WOR king将ggplot2中所有与缩放有关的代码放入一个单独的包中 - 这将使得以不同方式使用相同的缩放比较容易。进行中的代码见https://github.com/hadley/scales。