Use the fill function to make shaded regions of any color tint. Here is an example.
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1 from pylab import *
2
3 x = arange(10)
4 y = x
5
6 # Plot junk and then a filled region
7 plot(x, y)
8
9 # Make a blue box that is somewhat see-through
10 # and has a red border.
11 # WARNING: alpha doesn't work in postscript output....
12 fill([3,4,4,3], [2,2,4,4], 'b', alpha=0.2, edgecolor='r')
