physically stretch plot in horizontal direction in python

I want a simple x,y plot created with matplotlib stretched physically in x-direction.
The intention is to get a result were it is easier for me to detect features in the signal.

So I don't want to change any scales or values or limits. Just change the distance between two gridpoint in my output file...

I want to do that on four subplots which should have the same size afterwards.

Thanks in advance... I tried for hours now and I think one of you could probably help me...

David Zwicker already solved my problem in this special case, thanks a lot for that, but in general... If I plot 2 subplots like in this code:

fig = plt.figure()

ax1 = fig.add_subplot(1,2,1)

plot(u_av,z)

ax2 = fig.add_subplot(1,2,2)

plot(pgrd_av,z)

clf()

and want to stretch only one of them. What can I do?

You can directly add axes to the canvas at an arbitrary position with plt.axes(). For instance:

ax1 = plt.axes([0, 0, 3, 0.5])
ax2 = plt.axes([0, 0.6, 1, 1])