This treemap is based on the geometry of Gosper curves and has a very high aspect ratio, being ordered and stable, in nature. It assumes that the weights are integers and that their sum is a square number and the regions of the map are rectilinear polygons and highly non-ortho-convex. This treemap is based on the geometry of space-filling curves which guarantee the aspect ratio to be the most at 4. These treemaps are based on Voronoi diagram calculations, where the algorithm is iterative and does not give an upper bound on the aspect ratio. When a constant aspect-ratio is required, Orthoconvex treemaps are can be built. In various treemaps, the aspect ratio cannot be constant and grows with the depth of the tree. These are made out of algorithms to use space in a way such that the aspect ratio which might be arbitrarily high in the case of rectangular treemaps can be controlled. Among the many tiling algorithms having been developed, the “squarified algorithm” is the one that keeps each rectangle as square as possible is the one most commonly used. To date, six primary rectangular treemap algorithms have been developed: There is a tiling algorithm that defines the way rectangles are divided and ordered into sub-rectangles. Use and explore with the different algorithms available with treemaps to determine which makes the most optimal use of your data in terms of the aspect ratio. 4 When you need to explore different types of representations which could custom suit your data As a result, they can legibly display thousands of items on the screen simultaneously. Treemaps are optimized to show lots of data, because it stretches to within its bounding box, as compared to circular charts where space that could be used to tell a story with your data is lost in the corners. Use treemaps to make efficient use of space. The downside to a Treemap is that it doesn't show the hierarchal levels as clearly as other charts that visualise hierarchal data (such as a Tree Diagram or Sunburst Diagram).3 When you require your hierarchical representation to occupy less space Treemaps are also great at comparing the proportions between categories via their area size.
![treemap chart data treemap chart data](https://i.stack.imgur.com/AUyaV.jpg)
This makes Treemaps a more compact and space-efficient option for displaying hierarchies, that gives a quick overview of the structure. Many tiling algorithms have been developed, but the "squarified algorithm" which keeps each rectangle as square as possible is the one commonly used.īen Shneiderman originally developed Treemaps as a way of visualising a vast file directory on a computer, without taking up too much space on the screen.
![treemap chart data treemap chart data](http://help.pyramidanalytics.com/Content/Root/MainClient/apps/Discover/PRO/Visualizations/Images/G2-VisType-0330-TreeMap_945x456.png)
The way rectangles are divided and ordered into sub-rectangles is dependent on the tiling algorithm used. If no quantity is assigned to a subcategory, then it's area is divided equally amongst the other subcategories within its parent category. Also, the area size of the parent category is the total of its subcategories.
![treemap chart data treemap chart data](https://www.data-to-viz.com/graph/treemap_files/figure-html/unnamed-chunk-1-1.png)
When a quantity is assigned to a category, its area size is displayed in proportion to that quantity and to the other quantities within the same parent category in a part-to-whole relationship. Each category is assigned a rectangle area with their subcategory rectangles nested inside of it.
![treemap chart data treemap chart data](https://media.nngroup.com/media/editor/2019/09/16/levels-of-hte-hierarchy.png)
Treemaps are an alternative way of visualising the hierarchical structure of a Tree Diagram while also displaying quantities for each category via area size.