Labelling Horizontal Line in ggplot2 Graphic in R (Example Code)
In this R tutorial you’ll learn how to draw a straight labeled line in a ggplot2 plot.
Setting up the Example
data(iris) # Loading iris data head(iris) # Sepal.Length Sepal.Width Petal.Length Petal.Width Species # 1 5.1 3.5 1.4 0.2 setosa # 2 4.9 3.0 1.4 0.2 setosa # 3 4.7 3.2 1.3 0.2 setosa # 4 4.6 3.1 1.5 0.2 setosa # 5 5.0 3.6 1.4 0.2 setosa # 6 5.4 3.9 1.7 0.4 setosa |
install.packages("ggplot2") # Install & load ggplot2 library("ggplot2") |
my_plot <- ggplot(iris, # ggplot2 Plot without horizontal line aes(x = Sepal.Length, y = Sepal.Width)) + geom_line() my_plot |
Example: Draw Horizontal Line with Label to ggplot2 Graphic
my_plot + # Adding horizontal line & label geom_hline(aes(yintercept = 3.15), col = "red") + geom_text(aes(min(Sepal.Length), 3.15, label = 3.15, vjust = - 1), col = "red") |
Related Articles
Have a look at the following R programming tutorials. They focus on topics such as graphics in R, ggplot2, and text elements: