title: Matplotlib will not show a polygon plot centered by default?
body: <p>For all types plots I've seen so far, <code>matplotlib</code> will automatically center them when no <code>xlim(), ylim()</code> values are given. Example:</p>
  
  <pre><code>import matplotlib.pyplot as plt
  A_pts = [(162.5, 137.5), (211.0, 158.3), (89.6, 133.7)]
  ax = plt.subplot(111)
  ax.scatter(*A_pts)
  plt.show()
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/OKq5am.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/OKq5am.png" alt="enter image description here"></a></p>
  
  <p>But when I plot a <code>Polygon</code></p>
  
  <pre><code>ax = plt.subplot(111)
  triangle = plt.Polygon(A_pts, fill=None, edgecolor='r')
  ax.add_patch(triangle)
  plt.show()
  </code></pre>
  
  <p>the plot window is shown with limits <code>[0, 1]</code> for both axis, which results in the polygon not being visible. I have to explicitly pass proper limits so that it will show in the plot window</p>
  
  <pre><code>ax.set_xlim(80, 250)
  ax.set_ylim(120, 170)
  </code></pre>
  
  <p>Is this by design or am I missing something?</p>