gdf['href'] = '<a href="' + gdf.url + '">' + gdf.url + "</a>"
gdf['service_level'] = gdf.notes.str.split(', ').apply(lambda x: len([v for v in x if "all" in v]))
gdf['lines_served'] = gdf.line.str.split('-').apply(lambda x: len(x))
m = folium.Map(location=[40.75, -73.95], zoom_start=13)
folium.GeoJson(
    gdf,
    name="Subway Stations",
    marker=folium.Circle(radius=4, fill_color="orange", fill_opacity=0.4, color="black", weight=1),
    tooltip=folium.GeoJsonTooltip(fields=["name", "line", "notes"]),
    popup=folium.GeoJsonPopup(fields=["name", "line", "href", "notes"]),
    style_function=lambda x: {
        "fillColor": colors[x['properties']['service_level']],
        "radius": (x['properties']['lines_served'])*30,
    highlight_function=lambda x: {"fillOpacity": 0.8},
    zoom_on_click=True,
).add_to(m)
    props = feature.get('properties')
    markup = f"""
        <a href="{props.get('url')}">
            <div style="font-size: 0.8em;">
            <div style="width: 10px;
                        height: 10px;
                        border: 1px solid black;
                        border-radius: 5px;
                        background-color: orange;">
            {props.get('name')}
    return {"html": markup}
folium.GeoJson(
    gdf,
    name="Subway Stations",
    marker=folium.Marker(icon=folium.DivIcon()),
    tooltip=folium.GeoJsonTooltip(fields=["name", "line", "notes"]),
    popup=folium.GeoJsonPopup(fields=["name", "line", "href", "notes"]),
    style_function=style_function,
    zoom_on_click=True,
).add_to(m)
m = folium.Map(location=[40.75, -73.95], zoom_start=13)
marker_colors = ["red", "orange", "green", "blue"]
folium.GeoJson(
    gdf,
    name="Subway Stations",
    zoom_on_click=True,
    marker=folium.Marker(icon=folium.Icon(icon='star')),
    tooltip=folium.GeoJsonTooltip(fields=["name", "line", "notes"]),
    popup=folium.GeoJsonPopup(fields=["name", "line", "href", "notes"]),
    style_function=lambda x: {
        'markerColor': marker_colors[x['properties']['service_level']],
).add_to(m)