Learn about Radial Treemaps and create your own with Python
The Treemap concept
The “Treemap” was introduced by Ben Shneiderman at the University of Maryland in the early 1990s¹. Simply put, it is an efficient way to display hierarchical data as a set of nested rectangles. Although the concept is simple, the layout of the rectangles is subject to aesthetic preference, and various layout algorithms have been developed to improve the appearance of the final layout.
Given a hierarchy, a Treemap represents each branch of the hierarchy as a rectangle, which is then overlaid with smaller rectangles representing subbranches. Space in a Treemap is divided based on a specific attribute of the data (often size or value), and the area of each rectangle corresponds to the magnitude of the attribute, making it easier to compare different parts of the treemap. the hierarchy.
To account for the arrangement of rectangles, here are some of the common algorithms that govern the construction and final appearance of a Treemap:
- Squarified Treemaps² – creates rectangles as close to squares as possible by adjusting the aspect ratio of the rectangles
- Strip Treemaps³ – arranges rectangles into strips, horizontally or vertically, depending on the data hierarchy
- Slice-and-Dice⁴ – alternates between horizontal and vertical splits, which is simple but can create elongated rectangles
- Proportions: The size of each rectangle is proportional to the data point it represents, allowing for quick identification of larger and smaller elements.
- Lines and colors: Clever use of borders, their size and color, and buffers can demarcate hierarchical levels, while container colors are often used to represent different dimensions of data.
- Spatial efficiency – Treemaps…