title: Invert an axis in a matplotlib grafic
body: <p>How can I invert the y_axis? Z is a np.array.Thank you</p>
  
  <pre><code>Z=TempLake 
  
  X,Y=np.meshgrid(range(Z.shape[0]+1),range(Z.shape[1]+1)) 
  im = plt.pcolormesh(X,Y,Z.transpose(), cmap='hot') 
  plt.colorbar(im, orientation='horizontal') 
  plt.show() 
  </code></pre>
  
  <p>I have this:</p>
  
  <p><img src="https://i.stack.imgur.com/dWZOW.png" alt="enter image description here"></p>
  
  <p>I need this:
  <img src="https://i.stack.imgur.com/baMXH.png" alt="enter image description here"></p>