pygobject import error

---------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)
/home/lars/.local/lib/python3.4/site-packages/matplotlib/backends/backend_gtk3.py in <module>()
      9 try:
---> 10     import gi
     11 except ImportError:

ImportError: No module named 'gi'

During handling of the above exception, another exception occurred:

ImportError                               Traceback (most recent call last)
<ipython-input-4-4f2338257c9d> in <module>()
      1 import numpy as np
----> 2 import matplotlib.pyplot as plt

/home/lars/.local/lib/python3.4/site-packages/matplotlib/pyplot.py in <module>()
    107
    108 from matplotlib.backends import pylab_setup
--> 109 _backend_mod, new_figure_manager, draw_if_interactive, _show = pylab_setup()
    110
    111

/home/lars/.local/lib/python3.4/site-packages/matplotlib/backends/__init__.py in pylab_setup()
     30     # imports. 0 means only perform absolute imports.
     31     backend_mod = __import__(backend_name,
---> 32                              globals(),locals(),[backend_name],0)
     33
     34     # Things we pull in from all backends

/home/lars/.local/lib/python3.4/site-packages/matplotlib/backends/backend_gtk3agg.py in <module>()
      9
     10 from . import backend_agg
---> 11 from . import backend_gtk3
     12 from .backend_cairo import cairo, HAS_CAIRO_CFFI
     13 from matplotlib.figure import Figure

/home/lars/.local/lib/python3.4/site-packages/matplotlib/backends/backend_gtk3.py in <module>()
     10     import gi
     11 except ImportError:
---> 12     raise ImportError("Gtk3 backend requires pygobject to be installed.")
     13
     14 try:

ImportError: Gtk3 backend requires pygobject to be installed.