# example demonstrating how to draw a great circle on a map.
import matplotlib
from matplotlib.toolkits.basemap import Basemap
from pylab import *
# setup a mercator projection.
m = Basemap(-90.,30.,30.,60.,\
resolution='c',area_thresh=10000.,projection='merc',\
lat_ts=20.)
xsize = rcParams['figure.figsize'][0]
fig=figure(figsize=(xsize,m.aspect*xsize))
fig.add_axes([0.1,0.1,0.8,0.8])
ax = gca() # get current axis instance
ax.update_datalim(((m.llcrnrx, m.llcrnry),(m.urcrnrx,m.urcrnry)))
ax.set_xlim((m.llcrnrx, m.urcrnrx))
ax.set_ylim((m.llcrnry, m.urcrnry))
m.drawcoastlines()
m.fillcontinents()
# draw parallels
circles = [35,45,55]
m.drawparallels(circles,labels=[1,1,0,1])
# draw meridians
meridians = [-90,-60,-30,0,30]
m.drawmeridians(meridians,labels=[1,1,0,1])
# nylat, nylon are lat/lon of New York
nylat = 40.78
nylon = -73.98
# lonlat, lonlon are lat/lon of London.
lonlat = 51.53
lonlon = 0.08
# draw the great circle.
m.drawgreatcircle(nylon,nylat,lonlon,lonlat,linewidth=2,color='b')
title('Great Circle from New York to London')
show()
