This code generates the plot below:
data(mpg)
mg <- ggplot(mtcars, aes(x = mpg, y = wt)) + geom_point()
mg + facet_grid(vs + am ~ gear, margins = "vs")
The outer headers of y axis (e.g. 0,0) are the same but in different facets (grey rectangles). How can I display them as one single rectangle? I saw a similar post, but it added a label for the entire axis. Thanks