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import matplotlib.pyplot as plt
import numpy as np
try:
from mpl_toolkits.basemap import Basemap
have_basemap = True
except ImportError:
have_basemap = False
def plotmap():
# create figure
fig = plt.figure(figsize=(8,8))
# 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')
# 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)
# 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.
# (convert lons and lats to degrees first)
x, y = map(lons*180./np.pi, lats*180./np.pi)
# draw map boundary
map.drawmapboundary(color="0.9")
# draw graticule (latitude and longitude grid lines)
map.drawmeridians(np.arange(0,360,30),color="0.9")
map.drawparallels(np.arange(-90,90,30),color="0.9")
# 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+100000,ypt+100000,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.
# (downsample the image by 50% for speed)
map.bluemarble(scale=0.5)
def plotempty():
# create figure
fig = plt.figure(figsize=(8,8))
fig.text(0.5, 0.5, "Sorry, could not import Basemap",
horizontalalignment='center')
if have_basemap:
plotmap()
else:
plotempty()
plt.show()
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