This example visualizes world data on primary balance and economy using a choropleth map. The map projects countries with the `geoEquirectangular` projection via `d3.geoPath`, while fill colors are assigned by an ordinal color scale using a `schemeYlOrRd` palette. The data originates from a CSV file joined to the world-atlas TopoJSON. A custom legend lists the color scale's ordinal values, allowing users to click a legend item to update the map's color mapping.