Is there any way in ggplot2 to draw a continuous baseline across multiple facets? The closest I have found is to add a geom_hline to the plot. I would like the horizontal line to be continuous across all transmission types below.
The problem with this is that there are unrepresented levels of class leading to variable width bars. I think there was another post about handling that recently. You could calculate the summary before plotting, such that all combinations of trans and class are represented (ie with 0 where necessary) then do the above with stat='identity' for geom_bar. I think.
Thank you @nwerth. I want to maintain some separation between the groups - my actual data is considerably more dense than the example. Adding scale_x_discrete(expand=expand_scale(add=1)) does the trick!