How to color an area on a global map using python and basemap ?

Examples of how to color an area on a global map using python and basemap:

Plot a rectangular area

Using the function polygon (source: simple_basemap_example.py)

from mpl_toolkits.basemap import Basemap
from matplotlib.patches import Polygon
from matplotlib.collections import PatchCollection

import numpy as np
import matplotlib.pyplot as plt

fig = plt.figure()
ax=fig.add_axes([0.1,0.1,0.8,0.8])

m = Basemap(projection='cyl',llcrnrlat=-90,urcrnrlat=90, 
                llcrnrlon=-180,urcrnrlon=180,resolution='c')

m.drawcoastlines()
m.drawparallels(np.arange(-90,90,30),labels=[1,1,0,1], fontsize=8)
m.drawmeridians(np.arange(-180,180,30),labels=[1,1,0,1], rotation=45, fontsize=8)

patches = []
zone_A = np.array([[-138,60],[-122,60],[-122,30],[-138,30]])


patches.append(Polygon(zone_A))

ax.add_collection(PatchCollection(patches, facecolor='lightgreen', edgecolor='k', linewidths=0.5))

plt.title('How to color a rectangular area on a worl map using Basemap ?', fontsize=8)

plt.xlabel('Longitude', labelpad=40, fontsize=8)
plt.ylabel('Latitude', labelpad=40, fontsize=8)

plt.savefig('plot_world_map_using_matplotlib_03.png', bbox_inches='tight')

Plot two rectangular areas

Another example:

from mpl_toolkits.basemap import Basemap
from matplotlib.patches import Polygon
from matplotlib.collections import PatchCollection

import numpy as np
import matplotlib.pyplot as plt

fig = plt.figure()
ax=fig.add_axes([0.1,0.1,0.8,0.8])

m = Basemap(projection='cyl',llcrnrlat=-90,urcrnrlat=90, 
                llcrnrlon=-180,urcrnrlon=180,resolution='c')

m.drawcoastlines()
m.drawparallels(np.arange(-90,90,30),labels=[1,1,0,1], fontsize=8)
m.drawmeridians(np.arange(-180,180,30),labels=[1,1,0,1], rotation=45, fontsize=8)

patches = []
zone_A = np.array([[-138,60],[-122,60],[-122,30],[-138,30]])
zone_B = np.array([[-100,10],[-80,10],[-80,-20],[-100,-20]])

patches.append(Polygon(zone_A))
patches.append(Polygon(zone_B))

ax.add_collection(PatchCollection(patches, facecolor='lightgreen', edgecolor='k', linewidths=0.5))

plt.title('How to color an area on a global map with python and basemap ?', fontsize=8)

plt.xlabel('Longitude', labelpad=40, fontsize=8)
plt.ylabel('Latitude', labelpad=40, fontsize=8)

plt.savefig('plot_world_map_using_matplotlib_04.png', bbox_inches='tight')

Plot a triangular area

Example with the bermuda-triangle:

from mpl_toolkits.basemap import Basemap
from matplotlib.patches import Polygon
from matplotlib.collections import PatchCollection

import numpy as np
import matplotlib.pyplot as plt

fig = plt.figure()
ax=fig.add_axes([0.1,0.1,0.8,0.8])

m = Basemap(projection='cyl',llcrnrlat=-90,urcrnrlat=90, 
                llcrnrlon=-180,urcrnrlon=180,resolution='c')

m.drawcoastlines()
m.drawparallels(np.arange(-90,90,30),labels=[1,1,0,1], fontsize=8)
m.drawmeridians(np.arange(-180,180,30),labels=[1,1,0,1], rotation=45, fontsize=8)

patches = []
zone_A = np.array([[-80.226529,25.78910],[-66.1057427,18.4663188],[-64.781380,32.294887]])


patches.append(Polygon(zone_A))

ax.add_collection(PatchCollection(patches, facecolor='red', edgecolor='k', linewidths=0.5))

plt.title('How to color an area on a global map with python and basemap ?', fontsize=8)

plt.xlabel('Longitude', labelpad=40, fontsize=8)
plt.ylabel('Latitude', labelpad=40, fontsize=8)

plt.savefig('plot_world_map_using_matplotlib_05.png', bbox_inches='tight')

Plot a circular area

Plot a circular area with Paris as orgine:

from mpl_toolkits.basemap import Basemap
from matplotlib.patches import Polygon
from matplotlib.collections import PatchCollection

import numpy as np
import matplotlib.pyplot as plt
import math

fig = plt.figure()
ax=fig.add_axes([0.1,0.1,0.8,0.8])

m = Basemap(projection='cyl',llcrnrlat=-90,urcrnrlat=90, 
                llcrnrlon=-180,urcrnrlon=180,resolution='c')

m.drawcoastlines()
m.drawparallels(np.arange(-90,90,30),labels=[1,1,0,1], fontsize=8)
m.drawmeridians(np.arange(-180,180,30),labels=[1,1,0,1], rotation=45, fontsize=8)

patches = []

center = (2.35,48.85)
radius = 10

nb_points = 20

zone_A = []
for i in range(nb_points):
    zone_A.append((center[0]+radius * math.cos(2.*i*math.pi/nb_points),center[1]+radius*math.sin(2.*i*math.pi/nb_points)))

patches.append(Polygon(zone_A))

ax.add_collection(PatchCollection(patches, facecolor='red', edgecolor='k', linewidths=0.5))

plt.title('How to color an area on a global map with python and basemap ?', fontsize=8)

plt.xlabel('Longitude', labelpad=40, fontsize=8)
plt.ylabel('Latitude', labelpad=40, fontsize=8)

plt.savefig('plot_world_map_using_matplotlib_06.png', bbox_inches='tight')

References