Center Plot title in ggplot2

Question

This simple code (and all my scripts from this morning) has started giving me an off center title in ggplot2:

Ubuntu version: 16.04  R studio version: Version 0.99.896  R version: 3.3.2  GGPLOT2 version: 2.2.0 

I have freshly installed the above this morning to try and fix this...

dat <- data.frame( time = factor(c("Lunch","Dinner"), levels=c("Lunch","Dinner")), total_bill = c(14.89, 17.23) )  # Add title, narrower bars, fill color, and change axis labels ggplot(data=dat, aes(x=time, y=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") 

Answer 1

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))