How To Change Legend Key In R

R Programming

Changing the legend key in R can be a crucial step in creating visualizations that effectively convey your message. In this article, I will guide you through the process of customizing the legend key in R, sharing personal insights and tips along the way.

Understanding the Importance of Legend Key

Before we dive into the technical details, it’s essential to understand the significance of the legend key in data visualization. The legend key acts as a guide, providing context for the colors, shapes, or line types used in a plot. It helps viewers understand the data being presented and is particularly valuable when dealing with complex or layered visualizations.

Exploring the Code

When working with R, you may often find yourself needing to customize the legend key to better suit your visualization needs. Let’s consider a scenario where we have a scatter plot with different groups of points, each represented by a unique color in the legend key.

# Sample R code for creating a scatter plot with a legend
x <- c(1, 2, 3, 4, 5) y <- c(2, 3, 4, 5, 6) group <- c("A", "B", "C", "D", "E") plot(x, y, col = group, pch = 19, main = "Scatter Plot with Legend") legend("topright", legend = unique(group), col = unique(group), pch = 19)

Customizing the Legend Key

Now, let's focus on customizing the legend key. The legend() function in R provides several parameters that allow us to change the appearance and behavior of the legend. One such parameter is text, which enables us to modify the text displayed in the legend key to be more descriptive or tailored to our specific dataset.

# Customizing the text in the legend key
legend("topright", legend = unique(group), col = unique(group), pch = 19,
text.col = "blue", text.font = 2, bg = "lightgray", title = "Group Names")

By including the text.col, text.font, and bg parameters, we can change the color, font style, and background of the legend key text. Additionally, the title parameter allows us to add a title to the legend key, providing further clarity to the viewer.

Utilizing Additional Packages

In some cases, you may require more advanced customization options for your legend key. R offers various packages that can help you achieve this, such as the ggplot2 package, which provides extensive capabilities for creating sophisticated and visually appealing plots with customizable legends.


Changing the legend key in R involves understanding the diverse parameters available within the legend() function and utilizing additional packages like ggplot2 for advanced customization. By mastering these techniques, you can enhance the clarity and visual impact of your data visualizations, effectively communicating key insights to your audience.