title: How to plot an image with non-linear y-axis with Matplotlib using imshow?
body: <p>How can I plot an 2D array as an image with <a href="http://en.wikipedia.org/wiki/Matplotlib">Matplotlib</a> having the y scale relative to the power of two of the y value?</p>
  
  <p>For instance the first row of my array will have a height in the image of 1, the second row will have a height of 4, etc. (units are irrelevant)
  It's not simple to explain with words so look at this image please (that's the kind of result I want):</p>
  
  <p><a href="http://support.sas.com/rnd/app/da/new/802ce/iml/chap1/images/wavex1k.gif">alt text http://support.sas.com/rnd/app/da/new/802ce/iml/chap1/images/wavex1k.gif</a></p>
  
  <p>As you can see the first row is 2 times smaller that the upper one, and so on.</p>
  
  <p>For those interested in why I am trying to do this:</p>
  
  <p>I have a pretty big array (10, 700000) of floats, representing the discrete wavelet transform coefficients of a sound file. I am trying to plot the scalogram using those coefficients.
  I could copy the array x times until I get the desired image row size but the memory cannot hold so much information...</p>