Example of drawing choropleth using Matplotlib Basemap with Natural Earth boundary data

example_choropleth_world.py

# Uncomment this for notebooks
# %matplotlib inline

import matplotlib as mpl
from matplotlib.patches import Polygon
from matplotlib.collections import PatchCollection
from mpl_toolkits.basemap import Basemap
import numpy as np

# Country codes --> alpha
data = {"AU":0.2,'GB':0.6,'US':0.8}

# Set up the figure
fig,ax = plt.subplots(figsize=(22, 12))
m = Basemap(lon_0=0, projection='robin')
m.drawmapboundary(color='w')

# You can find this file here:
# http://www.naturalearthdata.com/downloads/10m-cultural-vectors/10m-admin-0-countries/
# Read the shapefile data
m.readshapefile('countries/natural-earth-10m/ne_10m_admin_0_countries_lakes', 
                'units', color='#444444', linewidth=.2)

# Fill countries in 'data' as red with appropriate alpha
# Otherwise fill countries as blue with random alpha
for info, shape in zip(m.units_info, m.units):
    # Get the country code, and assign colour and alpha
    country_code = info['ISO_A2'] 
    color = 'blue'
    alpha = np.random.random()
    if country_code in data:
        color = 'red'
        alpha = data[country_code]
    # Setup and add country patches
    patches = [Polygon(np.array(shape), True)]
    pc = PatchCollection(patches)
    pc.set_facecolor(color)
    pc.set_alpha(alpha)
    ax.add_collection(pc)