scales

The scales package provides the scaling infrastructure that converts data values into visual properties like positions, colors, and sizes, along with the inverse process of creating interpretable axes and legends. It powers the internal scaling system of ggplot2 but can also be used independently in any plotting system.

The package solves the problem of formatting and labeling plots through its flexible break and label functions. It includes built-in color palettes from systems like viridis and ColorBrewer that work across different plotting frameworks. Users can also define custom transformation functions for repeated use, making it straightforward to apply specialized scales like custom log transformations across multiple plots.