How do i scale my axes in matplotlib?

[Eric Holbrook]

I'm using matplotlib to generate (and save) plots of bandwidth data
from simulation logs. Since the simulations are of varying lengths, i
need a way to scale the axes so that every 100,000 points on the
X-axis are roughly equal to the height of the Y-axis. In other words,
if my X data varied from 0 to 575,000, my aspect ratio would be
roughly 6:1. If X goes from 200,000 to 400,000, then the aspect ratio
should be 2:1.

I've looked through the manuals, but i can't find out how to do
this. The 'axis' and 'axes' methods looked promising, but don't seem
to let me set an aspect ratio of the axes. Anyone know how to do this?

tia,
Eric