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Travis-CI:

# pylab_examples example code: hexbin_demo2.pyΒΆ

```"""
hexbin is an axes method or pyplot function that is essentially a
pcolor of a 2-D histogram with hexagonal cells.
"""

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.mlab as mlab

delta = 0.025
x = y = np.arange(-3.0, 3.0, delta)
X, Y = np.meshgrid(x, y)
Z1 = mlab.bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0)
Z2 = mlab.bivariate_normal(X, Y, 1.5, 0.5, 1, 1)
Z = Z2 - Z1  # difference of Gaussians

x = X.ravel()
y = Y.ravel()
z = Z.ravel()

if 1:
# make some points 20 times more common than others, but same mean
xcond = (-1 < x) & (x < 1)
ycond = (-2 < y) & (y < 0)
cond = xcond & ycond
xnew = x[cond]
ynew = y[cond]
znew = z[cond]
for i in range(20):
x = np.hstack((x, xnew))
y = np.hstack((y, ynew))
z = np.hstack((z, znew))

xmin = x.min()
xmax = x.max()
ymin = y.min()
ymax = y.max()

gridsize = 30

plt.subplot(211)
plt.hexbin(x, y, C=z, gridsize=gridsize, marginals=True, cmap=plt.cm.RdBu,
vmax=abs(z).max(), vmin=-abs(z).max())
plt.axis([xmin, xmax, ymin, ymax])
cb = plt.colorbar()
cb.set_label('mean value')

plt.subplot(212)
plt.hexbin(x, y, gridsize=gridsize, cmap=plt.cm.Blues_r)
plt.axis([xmin, xmax, ymin, ymax])
cb = plt.colorbar()
cb.set_label('N observations')

plt.show()
```

Keywords: python, matplotlib, pylab, example, codex (see Search examples)