>>> """
=============================================
Generate polygons to fill under 3D line graph
=============================================

Demonstrate how to create polygons which fill the space under a line
graph. In this example polygons are semi-transparent, creating a sort
of 'jagged stained glass' effect.
"""
... 
... from matplotlib.collections import PolyCollection
... import matplotlib.pyplot as plt
... import numpy as np
... from scipy.stats import poisson
... 
... # Fixing random state for reproducibility
... np.random.seed(19680801)
... 
... 
... def polygon_under_graph(x, y):
...     """
    Construct the vertex list which defines the polygon filling the space under
    the (x, y) line graph. This assumes x is in ascending order.
    """
...     return [(x[0], 0.), *zip(x, y), (x[-1], 0.)]
... 
... 
... ax = plt.figure().add_subplot(projection='3d')
... 
... x = np.linspace(0., 10., 31)
... lambdas = range(1, 9)
... 
... # verts[i] is a list of (x, y) pairs defining polygon i.
... verts = [polygon_under_graph(x, poisson.pmf(l, x)) for l in lambdas]
... facecolors = plt.colormaps['viridis_r'](np.linspace(0, 1, len(verts)))
... 
... poly = PolyCollection(verts, facecolors=facecolors, alpha=.7)
... ax.add_collection3d(poly, zs=lambdas, zdir='y')
... 
... ax.set(xlim=(0, 10), ylim=(1, 9), zlim=(0, 0.35),
...        xlabel='x', ylabel=r'$\lambda$', zlabel='probability')
... 
... plt.show()
...