title: Graph k-NN decision boundaries in Matplotlib
body: <p>How do I color the decision boundaries for a k-Nearest Neighbor classifier as seen here: <a href="https://i.stack.imgur.com/jz0hd.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/jz0hd.jpg" alt="enter image description here"></a>
  I've got the data for the 3 classes successfully plotted out using scatter (left picture).</p>
  
  <p>Image source: <a href="http://cs231n.github.io/classification/" rel="noreferrer">http://cs231n.github.io/classification/</a></p>