Treemap from bl.ocks.org
This treemap visualizes the hierarchical structure of the Flare data set, encoding each leaf node’s size by its rectangular area and grouping related categories by color. The view toggles between summing node values by size or by count, with animated transitions updating the layout over 750 milliseconds. Built with D3 v4, the example uses `d3.treemap`, `d3.hierarchy`, `d3.scaleOrdinal`, and `d3.treemapResquarify`, rendering the hierarchy as SVG rects and text elements with clip paths.