title: how to color data points based on some rules in matplotlib
body: <p>I have a signal, and I would like to color in red point which are too far from the mean of the signal. For example:</p>
  
  <pre><code>k=[12,11,12,12,20,10,12,0,12,10,11]
  x2=np.arange(1,12,1)
  plt.scatter(x2,k, label="signal")
  plt.show()
  </code></pre>
  
  <p>I would like to color in red the data points 20 and 0, and I give them a special label like "warning".
  I read <a href="https://stackoverflow.com/questions/7881994/matplotlib-how-to-change-data-points-color-based-on-some-variable">matplotlib: how to change data points color based on some variable</a>, but I am not sure how to apply it on my case </p>