Python Folium – Highlight regions with grouped polygons and custom tooltip fields

Hi everyone,
I’m trying to create an interactive map of the Alpes-Maritimes department (France, code 06) using Python and Folium.

I want to:

  • Display all communes of the department
  • Highlight 4 specific urban areas (Nice, Antibes, Saint-Laurent-du-Var, Le Cannet)
  • Assign a distinct color to each of these areas
  • Group nearby specific communes under those 4 cities (like a sector)

I’ve tried using a .geojson file with all communes and custom properties like "nom", "Secteur" and "Couleur", but I keep getting errors in Folium when applying the style function or tooltips (e.g., KeyError: 'Couleur' or missing fields).

I’m also working on macOS with Python 3.8, and had some compatibility issues with Fiona and geopandas, so I switched to using plain folium with simplified geometries.

Could anyone please help me to confirm the best way to build a sector-based map with Folium

Thanks in advance

Angely