Approaching ggplot2

2.1 映射坐标属性

library(ggplot2)

ggplot(mpg)+
  aes(x=cty,y=hwy,size=displ,color=class,shape=fl)

ggplot(data=mpg,mapping=aes(x=cty,y=hwy,size=displ,color=class,shape=fl))

2.2 映射其它属性

p<-ggplot(mpg,aes(x=cty,y=hwy))
p+geom_point(aes(size=cyl))

p+geom_point(aes(shape=manufacturer))

Warning: The shape palette can deal with a maximum of 6 discrete values because
more than 6 becomes difficult to discriminate; you have 15. Consider
specifying shapes manually if you must have them.

Warning: Removed 112 rows containing missing values (geom_point).

p+geom_point(aes(color=year))

2.3 映射的原理

p+geom_point(aes(color=class))

p+geom_point(aes(color="blue"))

p+geom_point(color="blue")

ggplot(mpg,aes(x=cty,y=hwy),color="blue")+
  geom_point()