#  注意aes(x=wt, y=mpg)中的wt不是字符"wt",因此它是属性字段名(例如，EXCel中字段名有Student,那就是Student，而不是"Student",也就是没有引号，虽然说字段的确是字符型)

# demo1.r

library(ggplot2)

ggplot(data=mtcars, aes(x=wt, y=mpg)) +

  geom_point() +

  labs(title="Automobile Data", x="Weight", y="Miles Per Gallon")

# demo2.r

library(ggplot2)

ggplot(data = mtcars, aes(x = wt, y = mpg)) +

  geom_point(pch = 17, color = "blue", size = 2) +

  geom_smooth(method = "lm", color = "red", linetype = 2) +

  labs(title = "Automobile Data", x = "weight", y = "Miles Per Gallon")

# demo3.r

library(ggplot2)

ggplot(mtcars, aes(x = wt, y = mpg)) +

  geom_boxplot(fill="cornflowerblue",

  color="black", notch=TRUE)+

  geom_point(position="jitter", color="blue", alpha=.5)+

  geom_rug(sides ="l", color="black") +

  labs(title = "Automobile Data", x = "weight", y = "Miles Per Gallon")

# demo4.r

library(ggplot2)

ggplot(mtcars, aes(x = wt, y = mpg)) +

  geom_violin(fill="lightblue") +

  geom_boxplot(fill="lightgreen", width=.2)  +

  labs(title = "Automobile Data", x = "weight", y = "Miles Per Gallon")

# demo5.r

library(ggplot2)

ggplot(mtcars, aes(x = wt, fill = mpg)) +

  geom_density(alpha=.3)