ggplot2：极坐标图中缺少坐标值

Question

I would like to make a polar plot of a bunch of points. So here is my code using ggplot2 :

x <- runif(min = -pi, max = pi, n = 100)
y <- runif(n = 100)
df1 <- data.frame(x = x, y = y)
library(ggplot2)
ggplot(df1, aes(y = y, x = x)) +  
  geom_point() + 
  ylim(0,1)  + 
  theme_light() +
  theme(legend.position="none",  panel.border=element_blank(), 
        axis.title = element_blank(), axis.text.y = element_blank()) + 
  scale_x_continuous(labels = paste(seq(-180,180,30)),
                     breaks = seq(-pi,pi, length=13)) + 
  coord_polar()

I get the following plot:

However, as we can see, the axis for 180 is missing. How do I get this? (I do not want to have the scale for y show up at the same time, or if it does, then to be able to control what gets shown there.)

Any suggestions?

Answer 1

You can add in a vertical line at pi but make it transparent. If you use xintercept=c(-pi,pi) you will get -180/180 as a label.

ggplot(df1, aes(y = y, x = x)) +  
  geom_point() + 
  ylim(0,1)  + 
  theme_light() +
  geom_vline(aes(xintercept=pi), col='transparent') + 
  theme(legend.position="none",  panel.border=element_blank(), 
        axis.title = element_blank(), axis.text.y = element_blank()) + 
  scale_x_continuous(labels = paste(seq(-180,180,30)),
                     breaks = seq(-pi,pi, length=13)) + 
  coord_polar()