title: Plotting a scatter plot in python where the z value corresponds to a color key
body: <p>I want to plot a scatter plot where each point has a color that corresponds to the value of a third array.
  The colors need to be specific to a key called colors.
  So if the z value was 4 then the color should be '#9C6BE1'</p>
  
  <pre><code>colors= ["#049FBB", "#5DF10A", "#BF5B3F", "#A95058", "#9C6BE1","#6CC43C","#7B3001", "#B3D407","#97CE66"] #hex colours
  
  x = [1,2,3,4]
  y = [3,4,8,6]
  z= [4,6,8,2]
  
  plt.scatter(x,y,c=c)
  </code></pre>
  
  <p>How do I plot each point to the color that corresponds to the value for z?</p>