Disable plot border (axes?)


I am trying to create a plot and I want to disable the black frame which
is drawn around the plot automatically. I achieved this with this setting:

mp.rcParams['axes.linewidth'] = 0

The problem is now, that I would like to have the dashed axes line, too.
Those dashed lines do appear on the top and the left of the plot, but
not on the lower and right border. What do I have to do to plot them
there, too?

See http://purecodes.org/stuff/sample.png

By the way, I am impressed by the library, I was searching quite a long
time for something like this when I was using Matlab. Great!