通过超过2种定义颜色的渐变填充或连续缩放颜色

Question

是否可以通过低于和高定义的参数来制作颜色渐变？

让我们说，关于这些数据：

df <- data.frame(a = 1:100, 
                 b = rnorm(100, mean = 1000, sd = 500))
ggplot(df) +
   geom_point(aes(a, b)) +
   scale_fill_continous(low = "white", high = "black")
         ## as "low" and "high" is all scale_fill_continous() funcion offer

设置低参数和高参数只会产生线性颜色渐变，但我想要更多的组合颜色渐变，让我们说从白色到蓝色再到黑色。

感谢您的关注和答案。

Answer 1

您可以尝试：

set.seed(123)
df <- data.frame(a=1:100, b=rnorm(100, mean = 1000, sd = 500))
ggplot(df,aes(x=a, y=b, col=b)) + geom_point() +  
  scale_colour_gradientn(colours = c("green", "blue","blue", "red","red", "yellow"),breaks = c(0,1000,2000,3000), limits=c(0,3000))

Answer 2

ggplot(data.frame(x=seq(along=x), y=rnorm(100, mean = 1000, sd = 500)), aes(x=x, y=y, colour=y)) + 
geom_point() + 
scale_colour_gradientn(values=c(0, 1000, 2000, 3000),
colours=c("green", "blue", "red", "yellow"),
rescaler=function(x, ...) x, oob=identity)

给出这个情节

Answer 3

colorpanel中的gplots功能非常适用于此。它产生2种或3种颜色之间的n种颜色（例如50）的光谱（中间颜色是可选的）：

library("gplots")
scale_fill_continuous <- colorpanel(50, "blue", "red") #2 colours
scale_fill_continuous <- colorpanel(50, "blue", "white", "red") #3 colours

还有各种预设功能，例如rainbow(50)，greenred(50)（中=黑）或bluered(50)（中=白）。

对于给出的例子：

#Generate a colour spectrum
library("gplots")
scale_fill_continuous <- colorpanel(300, "green", "purple", "yellow") 
#Generate data
set.seed(5)
data <- rnorm(100, mean = 1000, sd = 500)
mapping <- ceiling(data/100) #round to index in colour scale
coloured_data <- scale_fill_continuous[mapping] #map to colour sale