title: Three variables as heatmap
body: <p>I want to plot my data as a heatmap which has the following structure:</p>
  
  <p><code>X = [1,1,1,1,1,1,1,1,1,1],
  Y = [1,2,3,4,5,6,7,8,9,10]
  Z = [0.2, 0.33, 0.1, 0.25, 0.0, 0.9, 0.75, 0.88, 0.44, 0.95]</code></p>
  
  <p>The x and y-axis shall be represented by X and Y, while the 'heat' is represented by the values of Z.</p>
  
  <p>E.g. at coordinate (x,y) = (1,2) the intensity shall be 0.33
  How can this be achieved by using matplotlib? 
  Looking at posts which relate to the keyword heatmap or even to those related to the term contour map, I could not transfer it to this problem yet.</p>
  
  <p>Thank you in advance for any hints
  Dan</p>