Choropleth Map with Interactive Filtering
This interactive choropleth map displays world economic data using a D3.js SVG rendering with a `geoNaturalEarth1` projection and `geoPath`. A spectral ordinal color scale maps each country's economy category. Users can hover over legend items to filter the map, dimming non-selected countries to 10% opacity while highlighting matching ones. The visualization uses `d3.scaleOrdinal`, `d3.schemeSpectral`, and a custom `colorLegend` module, loading data from the world-atlas TopoJSON and TSV files.