Back in 1990, Ben Shneiderman, of the University of Maryland, wanted to visualize what was going on in his always-full hard drive. He wanted to know what was taking up so much space. Given the hierarchical structure of directories and files, he first tried a tree diagram. It got too big too fast to be useful though. Too many nodes. Too many branches.
The treemap was his solution. It's an area-based visualization where the size of each rectangle represents a metric since made popular by Martin Wattenberg's Map of the Market and Marcos Weskamp's newsmap.
Here's a really easy way to make your own treemap in just a couple lines of code. We're looking to make something like this:





