geopandas_and_geo_interface.md

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import folium

Using GeoPandas.GeoDataFrame in folium

GeoPandas is a project to add support for geographic data to pandas objects. (See https://github.com/geopandas/geopandas)

It provides (among other cool things) a GeoDataFrame object that represents a Feature collection. When you have one, you may be willing to use it on a folium map. Here's the simplest way to do so.

In this example, we'll use the same file as GeoPandas demo ; it's containing the boroughs of New York City.

import geopandas

boros = geopandas.read_file(
    "https://raw.githubusercontent.com/python-visualization/folium-example-data/main/new_york_boroughs.zip"
)

boros

To create a map with these features, simply put them in a GeoJson:

m = folium.Map([40.7, -74], zoom_start=10, tiles="cartodbpositron")

folium.GeoJson(boros).add_to(m)

m

Quite easy.

Adding style

Well, you can also take advantage of your GeoDataFrame structure to set the style of the data. For this, just create a column style containing each feature's style in a dictionary.

boros["style"] = [
    {"fillColor": "#ff0000", "weight": 2, "color": "black"},
    {"fillColor": "#00ff00", "weight": 2, "color": "black"},
    {"fillColor": "#0000ff", "weight": 2, "color": "black"},
    {"fillColor": "#ffff00", "weight": 2, "color": "black"},
    {"fillColor": "#00ffff", "weight": 2, "color": "black"},
]

boros

m = folium.Map([40.7, -74], zoom_start=10, tiles="cartodbpositron")

folium.GeoJson(boros).add_to(m)

m

Use any object with __geo_interface__

Folium should work with any object that implements the __geo_interface__ but be aware that sometimes you may need to convert your data to epsg='4326' before sending it to folium.

import fiona
import shapely

url = "https://raw.githubusercontent.com/python-visualization/folium-example-data/main/route_farol.gpx"
with fiona.open(url, "r", layer="tracks") as records:
    tracks = [shapely.geometry.shape(record["geometry"]) for record in records]

track = tracks[0]

m = folium.Map(tiles="cartodbpositron")
folium.GeoJson(track).add_to(m)

m.fit_bounds(m.get_bounds())

m