title: ImportError: No module named 'cairocffi'
body: <p>I am trying to run a sample code provided by scikit-rf (<a href="https://scikit-rf-web.readthedocs.io/" rel="nofollow noreferrer">https://scikit-rf-web.readthedocs.io/</a>) in a raspberry pi 3B. I installed all required libraries but I keep getting the error shown below.</p>
  
  <pre><code>Traceback (most recent call last):
    File "/usr/local/lib/python3.5/dist-packages/matplotlib-2.2.0-py3.5-linux-armv7l.egg/matplotlib/backends/backend_cairo.py", line 24, in &lt;module&gt;
      import cairocffi as cairo
  ImportError: No module named 'cairocffi'
  
  During handling of the above exception, another exception occurred:
  
  Traceback (most recent call last):
    File "/usr/local/lib/python3.5/dist-packages/matplotlib-2.2.0-py3.5-linux-armv7l.egg/matplotlib/backends/backend_cairo.py", line 27, in &lt;module&gt;
      import cairo
  ImportError: No module named 'cairo'
  
  During handling of the above exception, another exception occurred:
  
  Traceback (most recent call last):
    File "/home/pi/Desktop/Backup/scikit-rf-master/skrf/plotting.py", line 40, in &lt;module&gt;
      import matplotlib.pyplot as plb
    File "/usr/local/lib/python3.5/dist-packages/matplotlib-2.2.0-py3.5-linux-armv7l.egg/matplotlib/pyplot.py", line 115, in &lt;module&gt;
      _backend_mod, new_figure_manager, draw_if_interactive, _show = pylab_setup()
    File "/usr/local/lib/python3.5/dist-packages/matplotlib-2.2.0-py3.5-linux-armv7l.egg/matplotlib/backends/__init__.py", line 62, in pylab_setup
      [backend_name], 0)
    File "/usr/local/lib/python3.5/dist-packages/matplotlib-2.2.0-py3.5-linux-armv7l.egg/matplotlib/backends/backend_gtk3agg.py", line 10, in &lt;module&gt;
      from .backend_cairo import cairo, HAS_CAIRO_CFFI
    File "/usr/local/lib/python3.5/dist-packages/matplotlib-2.2.0-py3.5-linux-armv7l.egg/matplotlib/backends/backend_cairo.py", line 29, in &lt;module&gt;
      raise ImportError("cairo backend requires that cairocffi or pycairo "
  ImportError: cairo backend requires that cairocffi or pycairo is installed
  </code></pre>
  
  <p>I did install cairocffi using</p>
  
  <pre><code>pip install cairocffi
  </code></pre>
  
  <p>Entering <code>pip freeze</code> shows cairocff but this doesn't seem to help. Apologies as I am quite new to python.</p>