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))
As stated in the answer by Henrik, titles are left-aligned by default starting with ggplot 2.2.0. Titles can be centered by adding this to the plot:
theme(plot.title = element_text(hjust = 0.5))
However, if you create many plots, it may be tedious to add this line everywhere. One could then also change the default behaviour of ggplot with
theme_update(plot.title = element_text(hjust = 0.5))
Once you have run this line, all plots created afterwards will use the theme setting plot.title = element_text(hjust = 0.5) as their default:
theme_update(plot.title = element_text(hjust = 0.5))
ggplot() + ggtitle(“Default is now set to centered”)
To get back to the original ggplot2 default settings you can either restart the R session or choose the default theme with
theme_set(theme_gray())