fix bug

well, the columns here should be rows, as we want to give different colors by row index.
there is no problem in this example, because the matrix here is 5*5.
But if the length of rows is bigger than that of columns, it will raise Exception, such as
plt.bar(index, data[row], bar_width, bottom=y_offset, color=colors[row])
IndexError: index 2 is out of bounds for axis 0 with size 2

examples/pylab_examples/table_demo.py

@@ -18,7 +18,7 @@
 value_increment = 1000
 
 # Get some pastel shades for the colors
-colors = plt.cm.BuPu(np.linspace(0, 0.5, len(columns)))
+colors = plt.cm.BuPu(np.linspace(0, 0.5, len(rows)))
 n_rows = len(data)
 
 index = np.arange(len(columns)) + 0.3