This example visualizes six French cities on a Mercator map, encoding each location with a circle whose size corresponds to a numeric value and whose fill pattern distinguishes three categorical groups (A, B, C). The map uses `d3.geoMercator` and `d3.geoPath` to project and draw France from a GeoJSON source, while the textures library generates distinct striped patterns via `textures.lines()` for each group. Circles are positioned with the projection, sized via `d3.scaleLinear`, and styled with dashed black strokes and transparent fills to emphasize the pattern overlays.