Examples
--------
>>> import numpy as np
>>> from scipy.stats import levy
>>> import matplotlib.pyplot as plt
>>> fig, ax = plt.subplots(1, 1)

Calculate the first four moments:

>>> mean, var, skew, kurt = levy.stats(moments='mvsk')

Display the probability density function (``pdf``):

>>> # `levy` is very heavy-tailed.
>>> # To show a nice plot, let's cut off the upper 40 percent.
>>> a, b = levy.ppf(0), levy.ppf(0.6)
>>> x = np.linspace(a, b, 100)
>>> ax.plot(x, levy.pdf(x),
...        'r-', lw=5, alpha=0.6, label='levy pdf')

Alternatively, the distribution object can be called (as a function)
to fix the shape, location and scale parameters. This returns a "frozen"
RV object holding the given parameters fixed.

Freeze the distribution and display the frozen ``pdf``:

>>> rv = levy()
>>> ax.plot(x, rv.pdf(x), 'k-', lw=2, label='frozen pdf')

Check accuracy of ``cdf`` and ``ppf``:

>>> vals = levy.ppf([0.001, 0.5, 0.999])
>>> np.allclose([0.001, 0.5, 0.999], levy.cdf(vals))
True

Generate random numbers:

>>> r = levy.rvs(size=1000)

And compare the histogram:

>>> # manual binning to ignore the tail
>>> bins = np.concatenate((np.linspace(a, b, 20), [np.max(r)]))
>>> ax.hist(r, bins=bins, density=True, histtype='stepfilled', alpha=0.2)
>>> ax.set_xlim([x[0], x[-1]])
>>> ax.legend(loc='best', frameon=False)
>>> plt.show()

c