From the release news of ggplot 2.2.0
: "The main plot title is now left-aligned to better work better with a subtitle". See also the plot.title
argument in ?theme
: "left-aligned by default".
As pointed out by @J_F, you may add theme(plot.title = element_text(hjust = 0.5))
to center the title.
ggplot() +
ggtitle("Default in 2.2.0 is left-aligned")
ggplot() +
ggtitle("Use theme(plot.title = element_text(hjust = 0.5)) to center") +
theme(plot.title = element_text(hjust = 0.5))