title: Adding a crosshair or marker to a matplotlib contour plot
body: <p>I'm plotting a NumPy array as a contour plot using matplotlib:</p>
  
  <pre><code>import numpy as np
  import matplotlib.pyplot as plt
  
  plt.contour(array, linewidths = 1, colors = 'k')
  plt.contourf(array, cmap = plt.cm.jet)
  plt.colorbar()
  plt.show()
  </code></pre>
  
  <p>I would like to add a 'crosshair' or another marker to denote the maximum value in the array which is given by:</p>
  
  <pre><code>maxi = np.max(array)
  </code></pre>
  
  <p>How should I go about doing this?</p>