ggplot2：如何使用geom_jitter和geom_point控制点颜色？

Question

This is related to the question here . However, I'm not trying to make a boxplot , but a scatterplot in ggplot2 , but adding the argument geom_jitter() adds black dots which seem to be non-related to my dataset.

Here's an example using the mpg data pack :

This is a simple scatterplot, that looks a bit "too clean"

gmpg<-ggplot(data=mpg, aes(x=hwy, y=cty))
gmpg+geom_point(aes(col=manufacturer))

Which produces this:

Now, if I add the argument jitter, this is what happens

gmpg+geom_point(aes(col=manufacturer))+geom_jitter()

I've tried reducing the alpha etc., but the black dots remain. What on earth are these and how do I remove them?

Answer 1

There is no need to assign a new aesthetic mapping in the geom_* functions. This should work:

gmpg <- ggplot(data=mpg, aes(x=hwy, y=cty, col=manufacturer))
gmpg + geom_point() + geom_jitter()

Answer 2

不需要在其中添加geom_point（），geom_jitter（）就足够了。

ggplot(mpg,aes(cty,hwy,color=manufacturer))+geom_jitter();