# Hinton diagramsΒΆ

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) / max_weight)
rect = plt.Rectangle([x - size / 2, y - size / 2], size, size,
facecolor=color, edgecolor=color)

ax.autoscale_view()
ax.invert_yaxis()

if __name__ == '__main__':
# Fixing random state for reproducibility
np.random.seed(19680801)

hinton(np.random.rand(20, 20) - 0.5)
plt.show()


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