Radar Chart
This example presents five radar charts, one per San Francisco neighborhood, comparing the proportions of emergency call types: potentially life-threatening, alarm, fire, non-life-threatening, and other. Each chart plots a single series of data points, drawn as an SVG polygon using custom D3 functions, with axes and level rings. The code builds each radar chart from CSV data parsed in JavaScript, applying different colors per neighborhood and enabling hover interactions that highlight the focused area while dimming others. The implementation relies on D3 v3 for selections, transitions, and mouse events.