A grouped barplot is a type of chart that displays quantities for different variables, grouped by another variable.
This tutorial explains how to create grouped barplots in R using the data visualization library ggplot2.
Grouped Barplot in ggplot2
Suppose we have the following data frame that displays the average points scored per game for nine basketball players:
#create data frame df <- data.frame(team=rep(c('A', 'B', 'C'), each=3), position=rep(c('Guard', 'Forward', 'Center'), times=3), points=c(14, 8, 8, 16, 3, 7, 17, 22, 26)) #view data frame df team position points 1 A Guard 14 2 A Forward 8 3 A Center 8 4 B Guard 16 5 B Forward 3 6 B Center 7 7 C Guard 17 8 C Forward 22 9 C Center 26
We can use the following code to create a grouped barplot that displays the points scored by each player, grouped by team and position:
library(ggplot2) ggplot(df, aes(fill=position, y=points, x=team)) + geom_bar(position='dodge', stat='identity')
Customizing a Grouped Barplot
We can also customize the title, axes labels, theme, and colors of the grouped barplot to make it look however we’d like:
library(ggplot2) ggplot(df, aes(fill=position, y=points, x=team)) + geom_bar(position='dodge', stat='identity') + theme_minimal() + labs(x='Team', y='Points', title='Avg. Points Scored by Position & Team') + theme(plot.title = element_text(hjust=0.5, size=20, face='bold')) + scale_fill_manual('Position', values=c('coral2', 'steelblue', 'pink'))
We can customize the appearance even more by using one of the themes in the ggthemes library. For example, we could use the Wall Street Journal Theme from this library:
install.packages('ggthemes') library(ggplot2) library(ggthemes) ggplot(df, aes(fill=position, y=points, x=team)) + geom_bar(position='dodge', stat='identity') + theme_wsj()
Refer to our Complete Guide to the Best ggplot2 Themes for even more themes.