Add location marker on plotted Geopandas Dataframe using Folium

Question

Context

I have an merged geodataframe of 1). Postalcode areas and 2). total amount of deliveries within that postalcode area in the city of Groningen called results. The geodataframe includes geometry that include Polygons and Multiploygons visualizing different Postal code areas within the city.

I am new to GeoPandas and therefore I've tried different tutorials including this one from the geopandas official website wherein I got introduced into interactive Folium maps, which I really like. I was able to plot my geodataframe using result.explore(), which resulted in the following map

The problem

So far so good, but now I want to simply place an marker using the folium libarty with the goal to calculate the distance between the marker and the postalcode areas. After some looking on the internet I found out in the quickstart guild that you need to create an folium.Map, then you need folium.Choropleth for my geodataframe and folium.Marker and add them to the folium.Map.

m = folium.Map(location=[53.21917, 6.56667], zoom_start=15)

folium.Marker(
    [53.210903, 6.598276], 
    popup="My marker"
).add_to(m)

folium.Choropleth(results, data=results, columns="Postcode", fill_color='OrRd', name="Postalcode areas").add_to(m)
folium.LayerControl().add_to(m)
m

But when try to run the above code I get the following error:

What is the (possible) best way?

Besides my failing code (which would be great if someone could help me out). I am curious if this is the way to do it (Folium map + marker + choropleth). Is it not possible to call geodataframe.explore() which results into the map in second picture and then just add an marker on the same map? I have the feeling that I am making it too difficult, there must be an better solution using Geopandas.

Answer 1

• you have not provided the geometry. Have found postal districts of Netherlands and used that
• explore() supports will draw a point as a marker with appropriate parameters
• hence two layers,
  • one is postal areas coloured using number of deliveries
  • second is point, with distance to each area calculated

import geopandas as gpd
import shapely.geometry
import pandas as pd
import numpy as np

geo_url = "https://geodata.nationaalgeoregister.nl/cbsgebiedsindelingen/wfs?request=GetFeature&service=WFS&version=2.0.0&typeName=cbs_provincie_2017_gegeneraliseerd&outputFormat=json"

gdf = gpd.read_file(geo_url).assign(
    deliveries=lambda d: np.random.randint(10**4, 10**6, len(d))
)

p = gpd.GeoSeries(shapely.geometry.Point(6.598276, 53.210903), crs="epsg:4386")

# calc distances to point
gdf["distance"] = gdf.distance(p.to_crs(gdf.crs).values[0])

# dataframe of flattened distances
dfp = pd.DataFrame(
    [
        "<br>".join(
            [f"{a} - {b:.2f}" for a, b in gdf.loc[:, ["statcode", "distance"]].values]
        )
    ],
    columns=["info"],
)

# generate colored choropleth
m = gdf.explore(
    column="deliveries", categorical=True, legend=False, height=400, width=400
)
# add marker with distances
gpd.GeoDataFrame(
    geometry=p,
    data=dfp,
).explore(m=m, marker_type="marker")