title: How to install matplotlib? [python]
body: <p>I have a problem when I want to install <code>matplotlib</code> via pip:<br>
  I did:   </p>
  
  <pre><code>$ sudo pip install matplotlib
  </code></pre>
  
  <p>Out:  </p>
  
  <pre><code>Requirement already satisfied: matplotlib in /usr/lib/python2.7/dist-packages (1.5.1)
  launchpadlib 1.10.3 requires testresources, which is not installed.
  paramiko 2.4.1 has requirement cryptography&gt;=1.5, but you'll have cryptography 1.2.3 which is incompatible.
  </code></pre>
  
  <p>So then I did:</p>
  
  <pre><code>$ sudo pip install cryptography
  </code></pre>
  
  <p>Out: <strong>same error as above.</strong></p>
  
  <p>Portion of code:</p>
  
  <pre><code>import sys
  print(sys.version)
  import matplotlib.pyplot as plt
  </code></pre>
  
  <p>Out:  </p>
  
  <pre><code>2.7.12 (default, Dec  4 2017, 14:50:18) 
  Traceback (most recent call last):
  [GCC 5.4.0 20160609]
  
  import matplotlib.pyplot as plt
  ImportError: No module named matplotlib.pyplot
  </code></pre>
  
  <p>What should I do?</p>
  
  <p>Thanks in advance.</p>