Revision: 8215
http://matplotlib.svn.sourceforge.net/matplotlib/?rev=8215&view=rev
Author: ryanmay
Date: 2010-04-01 03:40:51 +0000 (Thu, 01 Apr 2010)
Log Message:
-----------
Add example of Hinton plots, which are used to plot weight matrices.
Added Paths:
-----------
trunk/matplotlib/examples/api/hinton_demo.py
Added: trunk/matplotlib/examples/api/hinton_demo.py
===================================================================
--- trunk/matplotlib/examples/api/hinton_demo.py (rev 0)
+++ trunk/matplotlib/examples/api/hinton_demo.py 2010-04-01 03:40:51 UTC (rev 8215)
@@ -0,0 +1,59 @@
+#Initial idea from David Warde-Farley on the SciPy Cookbook
+import numpy as np
+import matplotlib.pyplot as plt
+from matplotlib.patches import Rectangle
+from matplotlib.ticker import NullLocator
+#from matplotlib.collections import RegularPolyCollection
+#from matplotlib.colors import BoundaryNorm, ListedColormap
+
+def hinton(W, maxWeight=None, ax=None):
+ """
+ Draws a Hinton diagram for visualizing a weight matrix.
+ """
+ if not ax:
+ fig = plt.figure()
+ ax = fig.add_subplot(1, 1, 1)
+
+ if not maxWeight:
+ maxWeight = 2**np.ceil(np.log(np.abs(W).max())/np.log(2))
+
+ ax.patch.set_facecolor('gray')
+ ax.set_aspect('equal', 'box')
+ ax.xaxis.set_major_locator(NullLocator())
+ ax.yaxis.set_major_locator(NullLocator())
+ cmap = ListedColormap(['black', 'white'])
+ norm = BoundaryNorm([-1., 0., 1.], cmap.N)
+
+ for (x,y),w in np.ndenumerate(W):
+ color = 'white' if w > 0 else 'black'
+ size = np.sqrt(np.abs(w))
+ rect = Rectangle([x - size / 2, y - size / 2], size, size,
+ facecolor=color, edgecolor=color)
+ ax.add_patch(rect)
+ ax.autoscale_view()
+
+ # Reverse the yaxis limits
+ ax.set_ylim(*ax.get_ylim()[::-1])
+
+## Potential way using polygon collections that just has an issue with
+## easily getting the squares scaled by the data.
+
+# height,width = W.shape
+# x = np.arange(width)
+# y = np.arange(height)
+# X,Y = np.meshgrid(x, y)
+# xy = np.array([X.flatten(),Y.flatten()]).T
+# scaled_data = W.flatten() / maxWeight
+
+# rect_col = RegularPolyCollection(4, rotation=np.pi/4,
+# sizes=np.abs(scaled_data) * 72 / ax.figure.get_dpi(), offsets=xy,
+# transOffset=ax.transData, norm=norm, cmap=cmap, edgecolor='none')
+# ax.add_collection(rect_col)
+# rect_col.set_array(scaled_data)
+# ax.autoscale_view()
+
+if __name__ == '__main__':
+ hinton(np.random.rand(20, 20) - 0.5)
+ plt.title('Hinton Example')
+ plt.show()
+
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