This example shows a hierarchical dataset rendered as a force-directed graph, where parent nodes are connected to child nodes by lines, and each leaf node displays its label text inside a circle sized by its value. The visualization uses d3.forceSimulation with forces for link distance, charge, centering, and collision, while text is fit to each circle by computing a font size based on the circle’s radius and the text length. Nodes and links are drawn as SVG elements, with data loaded from a CSV file via d3.csv and a stratify layout, and labels are added for leaves using underscore.js.