Tags / legend
Customizing Plot Symbols and Legends in R Base Plots
Understanding the Behavior of scale_color_discrete(drop = TRUE) in ggplot2: A Guide to Troubleshooting Missing Values
Creating Informative Scatterplots: Colored by Date with Legend
Adding Boxes for NA Values in ggplot2 Legends for Continuous Maps
Centering Values in Stacked Bar Plots with ggplot: A Comprehensive Guide
Missing Legends in ggplot2 and geom_line