"""

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

Create 3D histogram of 2D data

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

Demo of a histogram for 2 dimensional data as a bar graph in 3D.

"""

# This import registers the 3D projection, but is otherwise unused.

from mpl_toolkits.mplot3d import Axes3D # noqa: F401 unused import

import matplotlib.pyplot as plt

import numpy as np

# Fixing random state for reproducibility

np.random.seed(19680801)

fig = plt.figure()

ax = fig.add_subplot(111, projection='3d')

x, y = np.random.rand(2, 100) * 4

hist, xedges, yedges = np.histogram2d(x, y, bins=4, range=[[0, 4], [0, 4]])

# Construct arrays for the anchor positions of the 16 bars.

xpos, ypos = np.meshgrid(xedges[:-1] + 0.25, yedges[:-1] + 0.25, indexing="ij")

xpos = xpos.ravel()

ypos = ypos.ravel()

zpos = 0

# Construct arrays with the dimensions for the 16 bars.

dx = dy = 0.5 * np.ones_like(zpos)

dz = hist.ravel()

ax.bar3d(xpos, ypos, zpos, dx, dy, dz, zsort='average')

plt.show()