I’m trying to write Python code to detect if there are gaps between polygons.

To do this I simplify some polygon geometries to create gaps, then I thought I could recombine and count the number of boundaries, assuming the anything greater than 1 would indicate a gap:

import geopandas as gpd

gdf = gpd.read_file("ne_50m_admin_0_countries_lakes.shp")
gdf = gdf[gdf["SUBREGION"] == "Northern Africa"]


simplified = gdf.geometry.simplify(0.7)

combined_polygons = gpd.GeoDataFrame(geometry=simplified).dissolve().explode()

bounds = combined_polygons.boundary

In theory it works for examples like this:

But there are other cases where things don’t work as expected (increasing the ‘simplify’ value produces only one multilinestring present):

Can anyone recommend a better way of doing this?