title: matplotlib axis('tight') doesn't work?
body: <p>According to the <a href="https://matplotlib.org/api/_as_gen/matplotlib.axes.Axes.autoscale.html#matplotlib.axes.Axes.autoscale" rel="noreferrer">documentation</a>, <code>ax.autoscale(tight=True)</code> should</p>
  
  <blockquote>
    <p>If True, set view limits to data limits;</p>
  </blockquote>
  
  <p>With <a href="https://matplotlib.org/api/_as_gen/matplotlib.axes.Axes.axis.html#matplotlib.axes.Axes.axis" rel="noreferrer"><code>ax.axis('tight')</code></a> being similar:</p>
  
  <blockquote>
    <p>‘tight’   &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Limits set such that all data is shown</p>
  </blockquote>
  
  <p>(sic)</p>
  
  <p>And we even see that it works in the screenshots of <a href="https://stackoverflow.com/q/37558329/1143274">this question</a>.</p>
  
  <p>But no matter what I try, it doesn't seem to work with the following simple example. Here's what I typed into <code>jupyter-qtconsole</code>:</p>
  
  <pre><code>In [27]: f, ax = plt.subplots(1)
  
  In [28]: ax.plot([0, 1], [1, 0])
  Out[28]: [&lt;matplotlib.lines.Line2D at 0x825abf0&gt;]
  
  In [29]: ax.axis('tight')
  Out[29]: (-0.050000000000000003, 1.05, -0.050000000000000003, 1.05)
  
  In [30]: ax.autoscale(tight=True)
  
  In [31]: plt.axis('tight')
  Out[31]: (-0.050000000000000003, 1.05, -0.050000000000000003, 1.05)
  
  In [32]: plt.autoscale(tight=True)
  
  In [33]: ax.plot([0, 1], [1, 0])
  Out[33]: [&lt;matplotlib.lines.Line2D at 0x825a4d0&gt;]
  
  In [34]: ax.autoscale(enable=True, axis='x', tight=True)
  </code></pre>
  
  <p>Throughout these commands, the limits of the plot don't change:</p>
  
  <p><a href="https://i.stack.imgur.com/FQyFC.png" rel="noreferrer"><img src="https://i.stack.imgur.com/FQyFC.png" alt="margins visible"></a></p>
  
  <p>What might I be doing wrong?</p>