title: Adding 'unorthodox' axes labels to a pyplot
body: <p>I found <a href="https://scikit-learn.org/stable/auto_examples/model_selection/plot_confusion_matrix.html" rel="nofollow noreferrer">an excellent tutorial on drawing a heatmap for a confusion matrix</a>, but I want to add some errors of commission and omission on the sides. </p>
  
  <p>I'll try to explain using this image:</p>
  
  <p><a href="https://i.stack.imgur.com/4YiYz.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/4YiYz.png" alt="confusion matrix"></a></p>
  
  <p>This means: </p>
  
  <ol>
  <li><p>I need to insert a number beside each of the boxes containing 0, 6, and 9 just right of the right edge of the image, and to the left of the legend  </p></li>
  <li><p>I need to insert a number above the each of boxes containing 13, 0 and 0 just above the top edge of the image, just below the title.</p></li>
  </ol>
  
  <p>(so 6 numbers in total)</p>
  
  <p>Is this even possible? I know nothing about the plotting functions in Python, as I'm new to the language. It just seems like a very difficult task from where I'm standing.</p>