From http://stackoverflow.com/questions/10665163/draw-rectangle-add-patch-in-pylab-mode Plot a rectangle in pylab - matplotlib

plot_rectangle

>>> from pylab import *
>>> plot([1,3,2])
[<matplotlib.lines.Line2D object at 0x102bc8950>]
>>> gca()
<matplotlib.axes.AxesSubplot object at 0x102790cd0>
>>> gca().add_patch(Rectangle((1,1),1,1))
<matplotlib.patches.Rectangle object at 0x102790510>
>>> savefig("rect.png")