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from __future__ import (absolute_import, division, print_function)
import numpy as np
import sys
import matplotlib.pyplot as plt
from mpl_toolkits.basemap import Basemap
from mpl_toolkits.basemap import __version__ as basemap_version
# Tissot's Indicatrix (http://en.wikipedia.org/wiki/Tissot's_Indicatrix).
# These diagrams illustrate the distortion inherent in all map projections.
# In conformal projections, where angles are conserved around every location,
# the Tissot's indicatrix are all circles, with varying sizes. In equal-area
# projections, where area proportions between objects are conserved, the
# Tissot's indicatrix have all unit area, although their shapes and
# orientations vary with location.
# requires Basemap version 0.99.1
if basemap_version < '0.99.1':
raise SystemExit("this example requires Basemap version 0.99.1 or higher")
# create Basemap instances with several different projections
m1 = Basemap(llcrnrlon=-180,llcrnrlat=-80,urcrnrlon=180,urcrnrlat=80,
projection='cyl')
m2 = Basemap(llcrnrlon=-180,llcrnrlat=-80,urcrnrlon=180,urcrnrlat=80,
projection='mill')
m3 = Basemap(lon_0=-60,lat_0=45,projection='ortho')
m4 = Basemap(llcrnrlon=-180,llcrnrlat=-80,urcrnrlon=180,urcrnrlat=80,
projection='merc',lat_ts=20)
m5 = Basemap(lon_0=270,lat_0=90,boundinglat=5,projection='npstere')
m6 = Basemap(lon_0=270,lat_0=90,boundinglat=5,projection='nplaea')
m7 = Basemap(lon_0=0,projection='moll')
m8 = Basemap(lon_0=0,projection='robin')
m9 = Basemap(lon_0=0,projection='hammer')
m10 = Basemap(lon_0=0,projection='mbtfpq')
m11 = Basemap(lon_0=0,projection='eck4')
m12 = Basemap(lon_0=0,projection='kav7')
m13 = Basemap(lon_0=270,lat_0=90,boundinglat=5,projection='npaeqd')
for m in [m1,m2,m3,m4,m5,m6,m7,m8,m9,m10,m11,m12,m13]:
# make a new figure.
fig = plt.figure()
# draw "circles" at specified longitudes and latitudes.
for parallel in range(-70,71,20):
for meridian in range(-150,151,60):
poly = m.tissot(meridian,parallel,6,100,facecolor='green',zorder=10,alpha=0.5)
# draw meridians and parallels.
m.drawparallels(np.arange(-60,61,30),labels=[1,0,0,0])
m.drawmeridians(np.arange(-180,180,60),labels=[0,0,0,1])
# draw coastlines, fill continents, plot title.
m.drawcoastlines()
m.drawmapboundary(fill_color='aqua')
m.fillcontinents(color='coral',lake_color='aqua')
title = 'Tissot Diagram: projection = %s' % m.projection
sys.stdout.write(title+'\n')
plt.title(title)
plt.show()
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