#####################################
# pylab-free version of simpletest.py
#####################################
# set backend to Agg.
import matplotlib
matplotlib.use('Agg')
from matplotlib.backends.backend_agg import FigureCanvasAgg as FigureCanvas
from matplotlib.toolkits.basemap import Basemap
from matplotlib.figure import Figure
from matplotlib.mlab import meshgrid
import matplotlib.numerix as nx
import matplotlib.cm as cm
def load(fname,comments='%',delimiter=None):
"""
Load ASCII data from fname into an array and return the array (from pylab).
"""
if fname.endswith('.gz'):
import gzip
fh = gzip.open(fname)
else:
fh = file(fname)
X = []
numCols = None
for line in fh:
line = line[:line.find(comments)].strip()
if not len(line): continue
row = [float(val) for val in line.split(delimiter)]
thisLen = len(row)
if numCols is not None and thisLen != numCols:
raise ValueError('All rows must have the same number of columns')
X.append(row)
X = nx.array(X)
r,c = X.shape
if r==1 or c==1:
X.shape = max([r,c]),
return X
# read in topo data (on a regular lat/lon grid)
# longitudes go from 20 to 380.
etopo = nx.array(load('etopo20data.gz'),'d')
lons = nx.array(load('etopo20lons.gz'),'d')
lats = nx.array(load('etopo20lats.gz'),'d')
# create figure.
fig = Figure()
canvas = FigureCanvas(fig)
# create axes instance, leaving room for colorbar at bottom.
ax = fig.add_axes([0.125,0.175,0.75,0.75])
# create Basemap instance for Robinson projection.
# set 'ax' keyword so pylab won't be imported.
m = Basemap(projection='robin',lon_0=0.5*(lons[0]+lons[-1]),ax=ax)
# reset figure size to have same aspect ratio as map.
# fig will be 8 inches wide.
# (don't use createfigure, since that imports pylab).
fig.set_figsize_inches((8,m.aspect*8.))
# make filled contour plot.
x, y = m(*meshgrid(lons, lats))
cs = m.contourf(x,y,etopo,30,cmap=cm.jet)
# draw coastlines.
m.drawcoastlines()
# draw a line around the map region.
m.drawmapboundary()
# draw parallels and meridians.
m.drawparallels(nx.arange(-60.,90.,30.),labels=[1,0,0,0],fontsize=10)
m.drawmeridians(nx.arange(0.,420.,60.),labels=[0,0,0,1],fontsize=10)
# add a title.
ax.set_title('Robinson Projection')
# add a colorbar.
cax = fig.add_axes([0.125, 0.05, 0.75, 0.05],frameon=False)
fig.colorbar(cs, cax=cax, tickfmt='%d', orientation='horizontal',clabels=cs.levels[::3])
# save image (width 800 pixels with dpi=100 and fig width 8 inches).
canvas.print_figure('simpletest',dpi=100)
# done.
print 'image saved in simpletest.png'
