#geom_vline 图注标记：垂直线的画法
library(ggplot2)
library(ggthemes)
p <- ggplot(mtcars, aes(x = wt, y = mpg)) + geom_point()
p + geom_vline(xintercept = 5)
p + geom_vline(xintercept = 1:5)
wt
mtcars$wt
p + geom_vline(xintercept = 1:5, colour="green", linetype = "longdash")
p + geom_vline(aes(xintercept = wt))
p + geom_vline(aes(xintercept = wt)) + coord_equal()
p + geom_vline(aes(xintercept = wt)) + coord_flip()
p + geom_vline(aes(xintercept = wt)) + coord_polar()+theme_wsj()
p2 <- p + aes(colour = factor(cyl))
p2 + geom_vline(xintercept = 15)
p <- qplot(mpg, wt, data=mtcars, facets = vs ~ am)
vline.data <- data.frame(z = c(15, 20, 25, 30), vs = c(0, 0, 1, 1), am = c(0, 1, 0, 1))
library(ggthemes)
p + geom_vline(aes(xintercept = z), vline.data)+theme_wsj()

#geom_hline 图注标记：水平线的画法
p <- ggplot(mtcars, aes(x = wt, y=mpg)) + geom_point()

p + geom_hline(aes(yintercept=mpg))
p + geom_hline(yintercept=20)
p + geom_hline(yintercept=seq(10, 30, by=5))+theme_wsj()

# With coordinate transforms
p + geom_hline(aes(yintercept=mpg)) + coord_equal()
p + geom_hline(aes(yintercept=mpg)) + coord_flip()
p + geom_hline(aes(yintercept=mpg)) + coord_polar()

# To display different lines in different facets, you need to
# create a data frame.
p <- qplot(mpg, wt, data=mtcars, facets = vs ~ am)

hline.data <- data.frame(z = 1:4, vs = c(0,0,1,1), am = c(0,1,0,1))
p + geom_hline(aes(yintercept = z), hline.data)
unemp+geom_rect(aes(NULL,NULL,xmin=start,xmax=end,fill=party),ymin=yrng[1],ymax=yrng[2],
                data=presidential,alpha=0.2)+scale_fill_manual(values=c("blue","red"))