如何在R中的散点图中为每个类赋予颜色? [英] How to give color to each class in scatter plot in R?

问题描述

在数据集中，我想采用两个属性并创建监督的散点图.有谁知道如何给每个班级使用不同的颜色?

In a dataset, I want to take two attributes and create supervised scatter plot. Does anyone know how to give different color to each class ?

我正在尝试在plot命令中使用col == c("red","blue","yellow")，但是不确定是否像我再添加一种颜色一样正确，即使我只有3个类，该颜色也会出现在散点图中.

I am trying to use col == c("red","blue","yellow") in the plot command but not sure if it is right as if I include one more color, that color also comes in the scatter plot even though I have only 3 classes.

谢谢

推荐答案

以下是使用传统图形(和Dirk的数据)的解决方案:

Here is a solution using traditional graphics (and Dirk's data):

> DF <- data.frame(x=1:10, y=rnorm(10)+5, z=sample(letters[1:3], 10, replace=TRUE)) 
> DF
    x        y z
1   1 6.628380 c
2   2 6.403279 b
3   3 6.708716 a
4   4 7.011677 c
5   5 6.363794 a
6   6 5.912945 b
7   7 2.996335 a
8   8 5.242786 c
9   9 4.455582 c
10 10 4.362427 a
> attach(DF); plot(x, y, col=c("red","blue","green")[z]); detach(DF)

这依赖于DF$z是一个因素的事实，因此，当用DF$z进行子集设置时，其值将被视为整数.因此，颜色矢量的元素将随z的不同而变化，如下所示:

This relies on the fact that DF$z is a factor, so when subsetting by it, its values will be treated as integers. So the elements of the color vector will vary with z as follows:

> c("red","blue","green")[DF$z]
 [1] "green" "blue"  "red"   "green" "red"   "blue"  "red"   "green" "green" "red"    

您可以使用legend函数添加图例:

You can add a legend using the legend function:

legend(x="topright", legend = levels(DF$z), col=c("red","blue","green"), pch=1)

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