4.4 Scatter plots/bubble plots
The ggplot anatomy (Section 4.2) covered both scatter and strip plots (both created with
Another cool thing about this geom is that adding a size aesthetic makes it into a bubble plot.
For example, let’s size the points by population.
As you would expect from a “grammar of graphics plot”, this is as simple as adding
size = pop as an aesthetic:
With increased bubble sizes, there is some overplotting, so let’s make the points hollow (
shape = 1) and slightly transparent (
alpha = 0.5):
The resulting bubble plots are shown in Figure 4.6.
Alpha is an aesthetic to make geoms transparent, its values can range from 0 (invisible) to 1 (solid).