title: Permission denied error by installing matplotlib
body: <p>I installed <strong>opencv</strong> with all dependencies. After the installation I tried to import <strong>matplotlib</strong> for a simple example.</p>
  
  <p>Then I got the following error, when I tried to install matplotlib via pip with <code>pip install matplotlib</code>:</p>
  
  <pre><code>Could not install packages due to an EnvironmentError: [Errno 13] Permission denied: '/usr/local/lib/python3.5/dist-packages/kiwisolver.cpython-35m-x86_64-linux-gnu.so'
  Consider using the `--user` option or check the permissions.
  </code></pre>
  
  <p>What can I do to install matplotlib?</p>