title: python matplotlib: how to use fill_between with a colormap to fill the background of a 2d plot?
body: <p>I'm trying to make a simple 2d plot from a 3 column data sets e.g. y=f(x) and z=f(x). I want to plot xy and would like to display z using color. For example, the rectangular regions between [x1,x2, min(y), max(y)] ... will be filled by a background color depending on the value of z. I tried to use fill_between but could not associate a colormap with it. I'm new to matplotlib and python. I would very much appreciate your comments/suggestions.</p>
  
  <p>Edit: I don't have an accurate plot but I'll try to explain my query with the help of following figure   <a href="http://matplotlib.org/mpl_examples/pylab_examples/fill_between_demo_02.png" rel="nofollow">sample plot</a></p>
  
  <p>say between x=0.5 to x=1, z=1
              x=1.0, to x=1.5, z=2 ....</p>
  
  <p>so I would like to cover x=0.5 to x=1 (min(y) to max(y)] with some color that corresponds to z=1, and between x=1, x=1.5, z=2 and so on.. I want to show this variation using a colormap and to display this colorbar at the right side.</p>