Kieran Healy shows an oddity in dplyr when dealing with zero-value records:
That looks fine. You can see in each panel the 2015 column is 100% Men. If we were working on this a bit longer we’d polish up the x-axis so that the dates were centered under the columns. But as an exploratory plot it’s fine.
But let’s say that, instead of a column plot, you looked at a line plot instead. This would be a natural thing to do given that time is on the x-axis and so you’re looking at a trend, albeit one over a small number of years.
This is behavior I hadn’t run into, and it does seem a bit odd. On a totally unrelated note, Healy’s Data Visualization: A Practical Introduction is one of the best books on the topic.