Normally x-axis (horizontal) values increase to right
> and y-axis (vertical) values increase up the page.
> Is it easy/possible to reverse this for the y-axis??
> (So that y-values **decrease** up the page for some
> range?)
ylim(ymax, ymin)
OR
xlim(xmax, xmin)
See, for example, http://matplotlib.sf.net/examples/invert_axes.py