from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
import numpy as np
# set up orthographic map projection with
# perspective of satellite looking down at 50N, 100W.
# use low resolution coastlines.
map = Basemap(projection='ortho',lat_0=50,lon_0=-100,resolution='l')
# draw coastlines, country boundaries, fill continents.
map.drawcoastlines(linewidth=0.25)
map.drawcountries(linewidth=0.25)
map.fillcontinents(color='coral')
# draw the edge of the map projection region (the projection limb)
map.drawmapboundary()
# draw lat/lon grid lines every 30 degrees.
map.drawmeridians(np.arange(0,360,30))
map.drawparallels(np.arange(-90,90,30))
# lat/lon coordinates of five cities.
lats=[40.02,32.73,38.55,48.25,17.29]
lons=[-105.16,-117.16,-77.00,-114.21,-88.10]
cities=['Boulder, CO','San Diego, CA',
'Washington, DC','Whitefish, MT','Belize City, Belize']
# compute the native map projection coordinates for cities.
xc,yc = map(lons,lats)
# plot filled circles at the locations of the cities.
map.plot(xc,yc,'bo')
# plot the names of those five cities.
for name,xpt,ypt in zip(cities,xc,yc):
plt.text(xpt+50000,ypt+50000,name,fontsize=9)
# make up some data on a regular lat/lon grid.
nlats = 73; nlons = 145; delta = 2.*np.pi/(nlons-1)
lats = (0.5*np.pi-delta*np.indices((nlats,nlons))[0,:,:])
lons = (delta*np.indices((nlats,nlons))[1,:,:])
wave = 0.75*(np.sin(2.*lats)**8*np.cos(4.*lons))
mean = 0.5*np.cos(2.*lats)*((np.sin(2.*lats))**2 + 2.)
# compute native map projection coordinates of lat/lon grid.
x, y = map(lons*180./np.pi, lats*180./np.pi)
# contour data over the map.
cs = map.contour(x,y,wave+mean,15,linewidths=1.5)
# as above, but use blue marble image as map background.
fig = plt.figure()
map.drawmapboundary()
map.drawmeridians(np.arange(0,360,30))
map.drawparallels(np.arange(-90,90,30))
# plot filled circles at the locations of the cities.
map.plot(xc,yc,'wo')
# plot the names of five cities.
for name,xpt,ypt in zip(cities,xc,yc):
plt.text(xpt+50000,ypt+50000,name,fontsize=9,color='w')
# contour data over the map.
cs = map.contour(x,y,wave+mean,15,linewidths=1.5)
# draw blue marble image in background.
map.bluemarble()
plt.show()
