title: imshow when you are plotting data, not images. Realtion between aspect and extent?
body: <p>I am plotting a 2D data array with imshow in matplotlib. I have a problem trying to scale the resulting plot. The size of the array is 30x1295 points, but the extent in units are:
      <code>extent = [-130,130,0,77]</code>
  If I plot the array without the extent, I get the right plot, but if I use extent, I get this plot with the wrong aspect.
  It is a pretty beginner question, but there is always a first time: How I can control the aspect and the size of the plot at the same time?
  Thanks,</p>
  
  <p>Alex</p>
  
  <p>P.D. The code is, for the right case:
      <code>imshow(np.log10(psirhoz+1e-5),origin='lower')</code></p>
  
  <p>and for the wrong one:
      <code>imshow(np.log10(psirhoz+1e-5),origin='lower',
      extent =[z_ax.min(),z_ax.max(),rho_ax.min(),rho_ax.max()])</code></p>
  
  <p>I hope this clarify a bit things.</p>