如何用ggplot指定不同的颜色 [英] How to specify different colors with ggplot

问题描述

library(ggplot2)
p <- ggplot(mtcars, aes(wt, mpg))
p + geom_point(size=4)

假设您具有上面的scatterplot.您如何指定将>= 25 mpg的点绘制为red，一个between 20 and 25 green和0-20 blue?

Suppose you have the above scatterplot. How can you specify that the points that are >= 25 mpg will be plotted red, the one between 20 and 25 green and the 0-20 blue?

可以专门使用ggplot完成吗?

推荐答案

您可以分两个步骤进行操作:

You do this in two steps:

首先，您定义应具有不同颜色的组；通过将另一列添加到数据框或在aes内部.我将在此处使用aes

First, you define the groups that should have different colours; either by adding another column to the data frame or inside aes. I’ll use aes here:

aes(wt, mpg, color = cut(mpg, breaks = c(0, 20, 25, Inf)))

第二，通过指定手动颜色或填充比例:

Secondly, by specifying a manual colour or fill scale:

scale_color_manual(values = c('blue', 'green', 'red'),
                   limits = c('(0,20]', '(20,25]', '(25,Inf]'))

这指定要使用的颜色(values)以及将其分配给(limits)的标签；这些是cut生成的分组的名称.

This specifies which colours to use (values) and which labels to assign them to (limits); these are the names of the grouping generated by cut.

在一起:

ggplot(mtcars) +
    aes(wt, mpg, color = cut(mpg, breaks = c(0, 20, 25, Inf))) +
    geom_point(size = 4) +
    scale_color_manual(values = c('blue', 'green', 'red'),
                       limits = c('(0,20]', '(20,25]', '(25,Inf]'))

您可以通过将分组作为单独的列添加到数据中，或通过提供guides函数调用来改善图例标题:

You can improve the legend title by adding the grouping as a separate column to your data, or by providing a guides function call:

guides(color = guide_legend(title = 'mpg range'))

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