如何在GGPLOT的geom_jitter()上添加geom_smooth()或stat_smooth()

Question

我有以下脚本：

require(datasets)
data(ToothGrowth)
library(ggplot2)
ToothGrowth$dose <- as.factor(ToothGrowth$dose)
p <- ggplot(ToothGrowth, aes(x=dose, y=len, color=dose, shape=dose)) + 
  geom_jitter(position=position_jitter(0.2))+
  labs(title="Plot of length  by dose",x="Dose (mg)", y = "Length") +   stat_summary(fun.data=mean_sdl, size=0.6, geom="pointrange", color="black") 
p + theme_classic() +
    theme(axis.line.x = element_line(colour = 'black', size=0.5, linetype='solid'),
          axis.line.y = element_line(colour = 'black', size=0.5, linetype='solid'))

如下图所示：

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我的问题是，如何为上面的黑色(均值)点添加smoothing line？

我尝试添加stat_smooth()，但不起作用。

Answer 1

如果您将dose保留为数字而不是将其设置为因子，则可以直接通过geom_smooth完成此操作。对于颜色和形状映射，您可以使用factor(dose)或使用不同的名称创建一个新的分类剂量变量。

data(ToothGrowth)
# New categorical dose for shapes and colors
ToothGrowth$Dose <- factor(ToothGrowth$dose)

ggplot(ToothGrowth, aes(x = dose, y = len, color = Dose, shape = Dose)) + 
    geom_jitter(position=position_jitter(0.2))+
    labs(title="Plot of length  by dose",x="Dose (mg)", y = "Length") +   
    stat_summary(fun.data=mean_sdl, size=0.6, geom="pointrange", color="black")  + 
    theme_classic() +
    theme(axis.line.x = element_line(colour = 'black', size=0.5, linetype='solid'),
         axis.line.y = element_line(colour = 'black', size=0.5, linetype='solid')) +
    geom_smooth(aes(x = dose, y = len), inherit.aes = FALSE, se = FALSE)

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如果您真的希望x轴是分类的，则需要通过对分类剂量变量使用as.numeric来绘制通过每个因子级别表示的整数的平滑线。这是使用x变量的等级而不是实际值绘制一条平滑线，这在您的实际情况下可能有意义，也可能没有意义。

ToothGrowth$Dose <- factor(ToothGrowth$dose)

ggplot(ToothGrowth, aes(x = Dose, y = len, color = Dose, shape = Dose)) + 
    geom_jitter(position=position_jitter(0.2))+
    labs(title="Plot of length  by dose",x="Dose (mg)", y = "Length") +   
    stat_summary(fun.data=mean_sdl, size=0.6, geom="pointrange", color="black")  + 
    theme_classic() +
    theme(axis.line.x = element_line(colour = 'black', size=0.5, linetype='solid'),
         axis.line.y = element_line(colour = 'black', size=0.5, linetype='solid')) +
    geom_smooth(aes(x = as.numeric(Dose), y = len), inherit.aes = FALSE, se = FALSE)

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Answer 2

require(datasets)
data(ToothGrowth)
library(ggplot2)
ToothGrowth$dose <- as.factor(ToothGrowth$dose)
p <- ggplot(ToothGrowth, aes(x=dose, y=len, color=dose, shape=dose)) + 
  geom_jitter(position=position_jitter(0.2))+
  labs(title="Plot of length  by dose",x="Dose (mg)", y = "Length") +   stat_summary(fun.data=mean_sdl, size=0.6, geom="pointrange", color="black") 
p + theme_classic() +
  theme(axis.line.x = element_line(colour = 'black', size=0.5, linetype='solid'),
        axis.line.y = element_line(colour = 'black', size=0.5, linetype='solid'))

lo <- loess(as.numeric(dose)~len,data=ToothGrowth)

p1 <- p+geom_line(aes(x=predict(lo)))

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