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pylab_examples example code: tricontour_vs_griddata.pyΒΆ

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../../_images/tricontour_vs_griddata.png
"""
Comparison of griddata and tricontour for an unstructured triangular grid.
"""
from __future__ import print_function
import matplotlib.pyplot as plt
import matplotlib.tri as tri
import numpy as np
from numpy.random import uniform, seed
from matplotlib.mlab import griddata
import time

seed(0)
npts = 200
ngridx = 100
ngridy = 200
x = uniform(-2,2,npts)
y = uniform(-2,2,npts)
z = x*np.exp(-x**2-y**2)

# griddata and contour.
start = time.clock()
plt.subplot(211)
xi = np.linspace(-2.1,2.1,ngridx)
yi = np.linspace(-2.1,2.1,ngridy)
zi = griddata(x,y,z,xi,yi,interp='linear')
plt.contour(xi,yi,zi,15,linewidths=0.5,colors='k')
plt.contourf(xi,yi,zi,15,cmap=plt.cm.rainbow,
             norm=plt.normalize(vmax=abs(zi).max(), vmin=-abs(zi).max()))
plt.colorbar() # draw colorbar
plt.plot(x, y, 'ko', ms=3)
plt.xlim(-2,2)
plt.ylim(-2,2)
plt.title('griddata and contour (%d points, %d grid points)' % (npts, ngridx*ngridy))
print ('griddata and contour seconds: %f' % (time.clock() - start))

# tricontour.
start = time.clock()
plt.subplot(212)
triang = tri.Triangulation(x, y)
plt.tricontour(x, y, z, 15, linewidths=0.5, colors='k')
plt.tricontourf(x, y, z, 15, cmap=plt.cm.rainbow,
                norm=plt.normalize(vmax=abs(zi).max(), vmin=-abs(zi).max()))
plt.colorbar()
plt.plot(x, y, 'ko', ms=3)
plt.xlim(-2,2)
plt.ylim(-2,2)
plt.title('tricontour (%d points)' % npts)
print ('tricontour seconds: %f' % (time.clock() - start))

plt.show()

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