"""

=========================

Fill under 3D line graphs

=========================

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.

"""

import math

import matplotlib.pyplot as plt

import numpy as np

gamma = np.vectorize(math.gamma)

N = 31

x = np.linspace(0., 10., N)

lambdas = range(1, 9)

ax = plt.figure().add_subplot(projection='3d')

facecolors = plt.colormaps['viridis_r'](np.linspace(0, 1, len(lambdas)))

for i, l in enumerate(lambdas):

# Note fill_between can take coordinates as length N vectors, or scalars

ax.fill_between(x, l, l**x * np.exp(-l) / gamma(x + 1),

x, l, 0,

facecolors=facecolors[i], alpha=.7)

ax.set(xlim=(0, 10), ylim=(1, 9), zlim=(0, 0.35),

xlabel='x', ylabel=r'$\lambda$', zlabel='probability')

plt.show()

# %%

# .. tags::

# plot-type: 3D,

# plot-type: fill_between,

# level: beginner