保存ggplot盒子圖的寬度當盒子數量不同時

Question

有沒有辦法在ggplot中保留盒子圖的寬度？默認情況下，寬度取決於圖中包含的框的數量。

Answer 1

如何手動設置x軸？

# Problem: different widths between these two plots 
p1 <- ggplot(mtcars, aes(x=factor(cyl), y=mpg)) + 
    geom_boxplot() 

p2 <- ggplot(mtcars[mtcars$cyl<8,], aes(x=factor(cyl), y=mpg)) + 
    geom_boxplot() 

# Solution: fix x axis 
p3 <- ggplot(mtcars[mtcars$cyl<8,], aes(x=factor(cyl), y=mpg)) + 
    geom_boxplot() + 
    scale_x_discrete(limits=c('4', '6', '8')) 

library(gridExtra) 
grid.arrange(p1, p2, p1, p3, ncol=2, main='Before', sub='After')