GeoPandas: Create a list of centroids of the first part of multi-polygon geography?

Question

I have a GeoDataframe containing multi-polygon geography. If I use the centroid function to find the centers, the results are not always located inside any of the polygons e.g. for a series of islands. So, how do I find the centroid of only the first polygon in the multi-polygon shape?

Answer 1

For the centroid of the first polygon of a MultiPolygon you can just do

mp[0].centroid

There are several ways to apply that, e.g. first limit each MultiPolygon in your dataframe to the first Polygon.

def keep_first(geo):
   if geo.geom_type == 'Polygon':
       return geo
   elif geo.geom_type == 'MultiPolygon':
       return geo[0]

df.geometry = df.geometry.apply(lambda _geo: keep_first(_geo))

df.centroid