Center Plot title in ggplot2

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())

The ggeasy package has a function called easy_center_title() to do just that. I find it much more appealing than theme(plot.title = element_text(hjust = 0.5)) and it's so much easier to remember.

ggplot(data = dat, aes(time, total_bill, fill = time)) +   geom_bar(colour = "black", fill = "#DD8888", width = .8, stat = "identity") +   guides(fill = FALSE) +  xlab("Time of day") +  ylab("Total bill") +  ggtitle("Average bill for 2 people") +  ggeasy::easy_center_title()

Note that as of writing this answer you will need to install the development version of ggeasy from GitHub to use easy_center_title(). You can do so by running remotes::install_github("jonocarroll/ggeasy").