updated file

create_multi_polygon.py

 import json
 import geopandas as gpd
 from shapely.geometry import Polygon, MultiPolygon, Point
+import fiona
 
 
 def find_center(mlp):
@@ -8,9 +9,9 @@ def find_center(mlp):
         area = 0
         for p in mlp.geoms:
             if p.area > area:
-                center = Point(p.centroid.x, p.centroid.y)
+                center = json.dumps([p.centroid.x, p.centroid.y])
     elif isinstance(mlp, Polygon):
-        center = Point(mlp.centroid.x, mlp.centroid.y)
+        center = json.dumps([mlp.centroid.x, mlp.centroid.y])
     else:
         raise TypeError('object not polygon nor multipolygon')
     return center
@@ -25,4 +26,4 @@ for climate in df['clmd_id'].unique():
     gdf = gdf.append(a, ignore_index=True)
 
 gdf['center'] = gdf['geometry'].apply(find_center)
-# gdf.to_file()
\ No newline at end of file
+gdf.to_file('output.json', driver='GeoJSON')