Using Leaflet and Folium to make interactive maps in Python


Interactive maps are useful for data exploration and communicating research. Leaflet, an open-source JavaScript library, facilitates the development of interactive maps, but is designed to be used via JavaScript. This tutorial provides a short demonstration of the folium package, which provides an easy to use interface to Leaflet for Python users.

Note: to see these maps execute these commands on your local machine

Objectives

  • Create a map centered at an inputted location
  • Create points on the map
  • Try out some of folium’s other features

Dependencies

  • Python
  • folium
  • pandas
!pip install folium
!pip install pandas
import folium
from folium.plugins import MarkerCluster
import pandas as pd

Show Map Centered at a Point

The most fundamental part of creating an interactive map is to allow users to input a location and view that location on the map; imagine how difficult it’d be to scroll/zoom to each specific point you want to view! Let’s create a map and center it at a specific geographic point such as Boulder, Colorado.

#Define coordinates of where we want to center our map
boulder_coords = [40.015, -105.2705]

#Create the map
my_map = folium.Map(location = boulder_coords, zoom_start = 13)

#Display the map
my_map

Adding Markers to the Map

Now that we’re able to display a map centeret at a point of our choosing, we can try adding some more content to the map via markers. Markers can be extremely useful for storing information about locations on the map such as cross streets, building information, etc. Using the same map, let’s add markers indicating where CU Boulder is as well as East Campus and the SEEC building.

#Define the coordinates we want our markers to be at
CU_Boulder_coords = [40.007153, -105.266930]
East_Campus_coords = [40.013501, -105.251889]
SEEC_coords = [40.009837, -105.241905]

#Add markers to the map
folium.Marker(CU_Boulder_coords, popup = 'CU Boulder').add_to(my_map)
folium.Marker(East_Campus_coords, popup = 'East Campus').add_to(my_map)
folium.Marker(SEEC_coords, popup = 'SEEC Building').add_to(my_map)

#Display the map
my_map

Other Features

Leaflet (or folium for our purposes) has some other pretty great features that you may find useful. There are some great tutorials that can be found online with examples that should be easily adaptable to your code. Additionally, folium can work with pandas dataframes in order to overlay data onto the interactive map. I’ve listed a few below and will go over some other features for the remainder of this notebook.

#Adding a tileset to our map
map_with_tiles = folium.Map(location = boulder_coords, tiles = 'Stamen Toner')
map_with_tiles
#Using polygon markers with colors instead of default markers
polygon_map = folium.Map(location = boulder_coords, zoom_start = 13)

CU_Boulder_coords = [40.007153, -105.266930]
East_Campus_coords = [40.013501, -105.251889]
SEEC_coords = [40.009837, -105.241905]

#Add markers to the map
folium.RegularPolygonMarker(CU_Boulder_coords, popup = 'CU Boulder', fill_color = '#00ff40',
                            number_of_sides = 3, radius = 10).add_to(polygon_map)
folium.RegularPolygonMarker(East_Campus_coords, popup = 'EastCampus', fill_color = '#bf00ff',
                            number_of_sides = 5, radius = 10).add_to(polygon_map)
folium.RegularPolygonMarker(SEEC_coords, popup = 'SEEC Building', fill_color = '#ff0000',
                           number_of_sides = 8, radius = 10).add_to(polygon_map)

#Display the map
polygon_map

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