How to create bar chart using ggplot2 with chart sub-title in R?

There are different ways to express any chart. The more information we can provide in a chart, the better it is because a picture says thousand words. Since nobody likes to read a long-reports, we should have better reporting of charts. Therefore, we can add a chart title as well as chart sub-title in ggplot2 to help the readers.

Example

Consider the below data −

> set.seed(1)
> x<-rpois(20,5)
> table(x)
x
2 3 4 5 6 7 8 9 11
1 3 4 2 4 2 2 1  1
> df<-data.frame(x)

Loading ggplot2 package −

> library(ggplot2)

Creating a simple bar chart −

> ggplot(df,aes(x))+
+ geom_bar()

Output

Creating a bar chart with title and sub-title −

> ggplot(df,aes(x))+
+ geom_bar()+
+ ggtitle(expression(atop("Class Group", atop(italic("Frequency Bar Chart")))))

Output