text: import matplotlib.pyplot as plt
  import numpy as np
  from matplotlib import cm
  from matplotlib.colors import Normalize
  
  ANGLE_MAPPER = cm.ScalarMappable(norm=Normalize(vmin=-np.pi, vmax=np.pi))
  
  
  def hinton(matrix, max_weight=1.0, 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('lightgrey')
      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 = np.arctan2(w.real, w.imag)
          color = ANGLE_MAPPER.to_rgba(color)
          size = np.sqrt(np.abs(w) / max_weight)
          rect = plt.Rectangle([x - size / 2, y - size / 2], size, size,
                               facecolor=color, edgecolor=color)
          ax.add_patch(rect)
  
      ax.set_xlim((-max_weight / 2, matrix.shape[0] - max_weight / 2))
      ax.set_ylim((-max_weight / 2, matrix.shape[1] - max_weight / 2))
      ax.autoscale_view()
      ax.invert_yaxis()
  