Highlight / Draw a box around some of the plots when using `facet_grid` in ggplot2
问题 I am creating a matrix of plots similar to ggplot(mpg, aes(displ, hwy)) + geom_point() + facet_grid(rows = vars(cyl), cols = vars(drv)) Now, I would like to have some way to highlight some of the individual plots, say the ones where cyl is 5 or 6, and drv is f . So, ideally, this might look like this: But I would also be happy with those panels having a different look by setting ggtheme to classic or similar. However, it is very unclear to me how I can modify individually selected plots