tweaking location of xlabel

I just started using matplotlib and I am very impressed.

    > Thanks to the developers!

The easiest way to fix this is simply change the size of your axes,

The reason you are having trouble setting the y value of the xlabel is
that it is dynamically repositioned at draw time to make sure it is
not overlapping to tick labels. The Axis.LABELPAD parameter
determines the spacing between ticklabels and the xlabel

  ax.xaxis.LABELPAD = 10 # 5 is default

This should be exposed as an rc param, but is not currently.