from matplotlib.toolkits.basemap import Basemap, interp, shiftgrid
from pylab import *
import cPickle
# read in data on lat/lon grid.
datadict = cPickle.load(open('500hgt.pickle','rb'))
hgt = datadict['data']; lons = datadict['lons']; lats = datadict['lats']
# shift data so lons go from -180 to 180 instead of 0 to 360.
hgt,lons = shiftgrid(180.,hgt,lons,start=False)
# set up map projection (lambert azimuthal equal area).
m = Basemap(-135.,-20.,45.,-20.,
resolution='c',area_thresh=10000.,projection='laea',
lat_0=90.,lon_0=-90.)
# transform to map projection coordinates.
nx = 101; ny = 101
hgt,x,y = m.transform_scalar(hgt,lons,lats,nx,ny,returnxy=True)
fig = figure(figsize=(8,8))
plots = ['contour','pcolor']
for np,plot in enumerate(plots):
fig.add_subplot(1,2,np+1)
#fig.add_subplot(2,1,np+1)
# plot data.
print plot+' plot ...'
if plot == 'pcolor':
pcolor(x,y,hgt,shading='flat')
elif plot == 'imshow':
im = imshow(hgt,extent=(m.llcrnrx,m.urcrnrx,m.llcrnry,m.urcrnry),origin='lower')
elif plot == 'contour':
levels, colls = contour(x,y,hgt,15,linewidths=0.5,colors='k')
levels, colls = contourf(x,y,hgt,15,cmap=cm.jet,colors=None)
# set size of plot to match aspect ratio of map.
ax = gca()
l,b,w,h = ax.get_position()
b = 0.5 - 0.5*w*m.aspect; h = w*m.aspect
#l = 0.5 - 0.5*h/m.aspect; w = h/m.aspect
ax.set_position([l,b,w,h])
corners = ((m.llcrnrx,m.llcrnry), (m.urcrnrx,m.urcrnry))
ax.update_datalim( corners )
axis([m.llcrnrx, m.urcrnrx, m.llcrnry, m.urcrnry])
# draw map.
m.drawcoastlines(ax)
# draw parallels
delat = 30.
delon = 90.
circles = arange(10.,90.+delat,delat).tolist()
m.drawparallels(ax,circles,labels=[0,0,1,1])
# draw meridians
meridians = arange(0.,360.,delon)
m.drawmeridians(ax,meridians,labels=[1,1,1,1],fontsize=10)
title('500 hPa Height - '+plot,y=1.075)
show()
