>>> """
=======================
Animated 3D random walk
=======================

"""
... 
... import numpy as np
... import matplotlib.pyplot as plt
... import matplotlib.animation as animation
... 
... # Fixing random state for reproducibility
... np.random.seed(19680801)
... 
... 
... def random_walk(num_steps, max_step=0.05):
...     """Return a 3D random walk as (num_steps, 3) array."""
...     start_pos = np.random.random(3)
...     steps = np.random.uniform(-max_step, max_step, size=(num_steps, 3))
...     walk = start_pos + np.cumsum(steps, axis=0)
...     return walk
... 
... 
... def update_lines(num, walks, lines):
...     for line, walk in zip(lines, walks):
...         # NOTE: there is no .set_data() for 3 dim data...
...         line.set_data(walk[:num, :2].T)
...         line.set_3d_properties(walk[:num, 2])
...     return lines
... 
... 
... # Data: 40 random walks as (num_steps, 3) arrays
... num_steps = 30
... walks = [random_walk(num_steps) for index in range(40)]
... 
... # Attaching 3D axis to the figure
... fig = plt.figure()
... ax = fig.add_subplot(projection="3d")
... 
... # Create lines initially without data
... lines = [ax.plot([], [], [])[0] for _ in walks]
... 
... # Setting the axes properties
... ax.set(xlim3d=(0, 1), xlabel='X')
... ax.set(ylim3d=(0, 1), ylabel='Y')
... ax.set(zlim3d=(0, 1), zlabel='Z')
... 
... # Creating the Animation object
... ani = animation.FuncAnimation(
...     fig, update_lines, num_steps, fargs=(walks, lines), interval=100)
... 
... plt.show()
...