如何在R中生成数字到颜色的映射？ [英] How do I generate a mapping from numbers to colors in R?

问题描述

在R中，我可以轻松生成一个色带，例如colorRampPalette。下面产生了从蓝色到红色的五种颜色的序列：

In R, I can easily generate a color ramp, for example colorRampPalette. The following produces a sequence of five colors, from blue to red:

> mypal <- colorRampPalette( c( "blue", "red" ) )( 5 )
> mypal
[1] "#0000FF" "#3F00BF" "#7F007F" "#BF003F" "#FF0000"

如何轻松在此调色板上映射数字向量？假设我有一个介于0到10之间的数字向量，如下所示：

How can I easily map a vector of numbers on this palette? Say, I have a vector of numbers between 0 and 10, like this:

x <- c( 1, 9, 8.5, 3, 3.4, 6.2 )

我想要一个函数，例如 map2color ，这样当我运行 map2color（mypal，x）时，我得到

I would like a function, say map2color, such that when I run map2color( mypal, x ), I get

#0000FF, #FF0000, #FF0000, #3F00BF, #3F00BF, #BF003F

我通常会执行以下操作

mypalette[ findInterval( x, seq( 0, 10, length.out= 6 ), rightmost.closed= T ) ]

但是也许有更好的解决方法，会自动为数字矢量生成一个色阶。

but maybe there is a better solution OOB, automatically generating a color scale for a numeric vector.

推荐答案

我在R-Forge上的colourscheme软件包可以做到：

My colourscheme package on R-Forge does that:

https：//r-forge.r -project.org/projects/colourscheme/

其主要目的是创建映射数值va的函数引导（而不只是整数颜色数字）颜色。安装小插图后，它是最好的文档。

its primary purpose is to create functions that map numeric values (not just integer colour numbers) to colours. The vignette is the best documentation once you've got it installed.

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