ggplot2 Cheat Sheet:
Two Variables: Discrete x, Continuous y

library(ggplot2)

Columns

p <- ggplot(mpg, aes(class, hwy))
p <- p + geom_col()
print(p)

Box Plot

p <- ggplot(mpg, aes(class, hwy))
p <- p + geom_boxplot()
print(p)

Dot Plot

p <- ggplot(mpg, aes(class, hwy))
p <- p + geom_dotplot(binaxis = "y", stackdir = "center", dotsize = 0.3)
print(p)

Violin Plot

p <- ggplot(mpg, aes(class, hwy))
p <- p + geom_violin(scale = "area")
print(p)