无法在ggplot2中创建多个密度图的图例 [英] Cannot make legend for several density plots in ggplot2

问题描述

我使用ggplot2绘制了一些有传说的密度图，但我无法将图例添加到最终结果中。

  m <  -  ggplot（chickwts，aes（x = weight））
m + geom_density（kernel =gaussian，adjust = .3，color =green，size = 1）+ 
 geom_density =gaussian，adjust = 1，color =red，size = 1）+ 
 geom_density（kernel =gaussian，adjust = 5，color =blue，size = 1）+ 
 geom_density（内核=高斯，调整= 10，颜色=黄色，大小= 1）+ 
 geom_density（内核=高斯 
  

我已经使用了几个我在这里找到的语法，但没有一个不起作用。
谢谢。

解决方案

ggplot2 美学或传递给 aes（）函数的参数。通常，您会指定一个因子作为颜色美学，这会自动创建颜色图例。但是， chickwts 数据集中没有内置密度分组因子，因此您必须制作自己的比例和标签。

不是直接在 geom_density（）中定义颜色，您可以定义一个命名的颜色审美，在 scale_colour_manual（）中创建的自定义色彩比例如下：

  m <-ggplot（chickwts，aes（x = weight））
m + geom_density（kernel =gaussian，adjust = .3，aes（color =。3），size = 1）+ 
 geom_density（kernel =gaussian，adjust = 1，aes（color =1），size = 1）+ 
 geom_density（kernel =gaussian，adjust = 5，aes（color =5 ），size = 1）+ 
 geom_density（kernel =gaussian，adjust = 10，aes（color =10），size = 1）+ 
 geom_density（kernel =gaussian， adjust = 20，aes（color =20），size = 1）+ 
 scale_colour_manual（values = c（。3=green，1=red，5=蓝色，10=黄色，20=橙色），名称=密度）
  

I am using ggplot2 to have some density plots with legends, but I cannot add legend to my final result.

m <- ggplot(chickwts, aes(x = weight))
m + geom_density(kernel = "gaussian", adjust = .3, colour="green", size=1)+
  geom_density(kernel = "gaussian", adjust = 1, colour="red", size=1)+
  geom_density(kernel = "gaussian",adjust = 5, colour="blue", size=1)+
  geom_density(kernel = "gaussian",adjust = 10, colour="yellow", size=1)+
  geom_density(kernel = "gaussian",adjust = 20, colour="orange", size=1)

I have used several syntaxes which I have found here but none of them did not work. Thank you.

解决方案

ggplot2 bases its legends on aesthetics, or arguments passed to the aes() function. Ordinarily, you'd assign a factor as the color aesthetic, which would create the color legend automatically. However, there is no built-in density grouping factor in the chickwts dataset, so you have to make up your own scale and labels.

Instead of defining the color directly in geom_density(), you can define a named color aesthetic that corresponds to a custom color scale you create in scale_colour_manual(), like so:

m <- ggplot(chickwts, aes(x = weight))
m + geom_density(kernel = "gaussian", adjust = .3, aes(colour=".3"), size=1)+
  geom_density(kernel = "gaussian", adjust = 1, aes(colour="1"), size=1)+
  geom_density(kernel = "gaussian",adjust = 5, aes(colour="5"), size=1)+
  geom_density(kernel = "gaussian",adjust = 10, aes(colour="10"), size=1)+
  geom_density(kernel = "gaussian",adjust = 20, aes(colour="20"), size=1) + 
  scale_colour_manual(values=c(".3"="green", "1"="red", "5"="blue", "10"="yellow", "20"="orange"), name="Densities")

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