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specialty_plots example code: hinton_demo.pyΒΆ

```"""
Demo of a function to create Hinton diagrams.

Hinton diagrams are useful for visualizing the values of a 2D array (e.g.
a weight matrix): Positive and negative values are represented by white and
black squares, respectively, and the size of each square represents the
magnitude of each value.

Initial idea from David Warde-Farley on the SciPy Cookbook
"""
import numpy as np
import matplotlib.pyplot as plt

def hinton(matrix, max_weight=None, ax=None):
"""Draw Hinton diagram for visualizing a weight matrix."""
ax = ax if ax is not None else plt.gca()

if not max_weight:
max_weight = 2**np.ceil(np.log(np.abs(matrix).max())/np.log(2))

ax.patch.set_facecolor('gray')
ax.set_aspect('equal', 'box')
ax.xaxis.set_major_locator(plt.NullLocator())
ax.yaxis.set_major_locator(plt.NullLocator())

for (x,y),w in np.ndenumerate(matrix):
color = 'white' if w > 0 else 'black'
size = np.sqrt(np.abs(w))
rect = plt.Rectangle([x - size / 2, y - size / 2], size, size,
facecolor=color, edgecolor=color)