1 Goal


The goal of this tutorial is to center the title of a plot in ggplot.


2 Data import


# First we load the libraries
library(ggplot2)

# In this example we will use the open repository of plants classification Iris. 
data("iris")
str(iris)
## 'data.frame':    150 obs. of  5 variables:
##  $ Sepal.Length: num  5.1 4.9 4.7 4.6 5 5.4 4.6 5 4.4 4.9 ...
##  $ Sepal.Width : num  3.5 3 3.2 3.1 3.6 3.9 3.4 3.4 2.9 3.1 ...
##  $ Petal.Length: num  1.4 1.4 1.3 1.5 1.4 1.7 1.4 1.5 1.4 1.5 ...
##  $ Petal.Width : num  0.2 0.2 0.2 0.2 0.2 0.4 0.3 0.2 0.2 0.1 ...
##  $ Species     : Factor w/ 3 levels "setosa","versicolor",..: 1 1 1 1 1 1 1 1 1 1 ...
# Let's plot the petal length vs petal width
ggplot() + geom_point(data = iris, aes(x = Petal.Width, y = Petal.Length,color = Species))


3 Center the title


# Let's add a pretty decent title to the plot
# However the title is justified to the left :/
ggplot() + geom_point(data = iris, aes(x = Petal.Width, y = Petal.Length,color = Species)) +
  ggtitle("My dope plot")

# We can solve this by adjusting the title to be centered
# The instruction is a simple as intuitive 
# Problem solved
ggplot() + geom_point(data = iris, aes(x = Petal.Width, y = Petal.Length,color = Species)) +
  ggtitle("My dope plot")+
  theme(plot.title = element_text(hjust = 0.5))


4 Conclusion


In this tutorial we have learnt how to center the title of a plot in ggplot.