title: How to set matplotlib backend at vscode
body: <p>Ubuntu 19.10,
  VScode 1.42.0,
  python 3.7.6,
  anaconda 4.8.2,
  matplotlib 3.1.3</p>
  <p>It seems that <code>plt.show()</code> doesn't work, because the current matplotlib backend is <code>agg</code>.
  Running from the terminal, I can use <code>Qt4Agg</code>, but from the integrated terminal inside VScode I cannot change from <code>agg</code>.</p>
  <p>Tried the following:</p>
  <ol>
  <li>add <code>backend: Qt4Agg</code> at matplotlibrc</li>
  <li><code>__import__(&quot;matplotlib&quot;).use(&quot;Qt4Agg&quot;)</code><br />
  <code>__import__(&quot;matplotlib&quot;).use(&quot;Qt4Agg&quot;, warn=False, force=True)</code><br />
  <em>ImportError: Cannot load backend 'Qt4Agg' which requires the 'qt4' interactive framework, as 'headless' is currently running</em></li>
  <li><code>plt.switch_backend('Qt4Agg')</code><br />
  same <em>ImportError</em></li>
  <li><code>export MPLBACKEND=Qt4Agg</code> before running the command</li>
  </ol>
  <p>But, nothing worked. Any suggestions?<br />
  Thank you!</p>