Python 3: Installing gi package with pip

Question

I am trying to run this Matplotlib example using Python 3. To run this I needed to install gi first (I am using pyenv):

$ python --version
Python 3.6.1
$ pip --version
pip 9.0.1 from /home/hakon/.pyenv/versions/3.6.1/lib/python3.6/site-packages (python 3.6)
$ pip install gi
Collecting gi
  Downloading gi-1.2.tar.gz
Collecting requests (from gi)
  Downloading requests-2.16.0-py2.py3-none-any.whl (85kB)
    100% |████████████████████████████████| 92kB 959kB/s 
Collecting idna<2.6,>=2.5 (from requests->gi)
  Downloading idna-2.5-py2.py3-none-any.whl (55kB)
    100% |████████████████████████████████| 61kB 1.2MB/s 
Collecting chardet<3.1.0,>=3.0.2 (from requests->gi)
  Downloading chardet-3.0.3-py2.py3-none-any.whl (133kB)
    100% |████████████████████████████████| 143kB 1.8MB/s 
Collecting urllib3<1.22,>=1.21.1 (from requests->gi)
  Downloading urllib3-1.21.1-py2.py3-none-any.whl (131kB)
    100% |████████████████████████████████| 133kB 1.8MB/s 
Collecting certifi>=2017.4.17 (from requests->gi)
  Downloading certifi-2017.4.17-py2.py3-none-any.whl (375kB)
    100% |████████████████████████████████| 378kB 284kB/s 
Installing collected packages: idna, chardet, urllib3, certifi, requests, gi
  Running setup.py install for gi ... done
Successfully installed certifi-2017.4.17 chardet-3.0.3 gi-1.2 idna-2.5 requests-2.16.0 urllib3-1.21.1

Now, running the example:

$ python toolmanager.py 
Traceback (most recent call last):
  File "./toolmanager.py", line 8, in 
    import matplotlib.pyplot as plt
  File "/home/hakon/.pyenv/versions/3.6.1/lib/python3.6/site-packages/matplotlib/pyplot.py", line 115, in 
    _backend_mod, new_figure_manager, draw_if_interactive, _show = pylab_setup()
  File "/home/hakon/.pyenv/versions/3.6.1/lib/python3.6/site-packages/matplotlib/backends/__init__.py", line 32, in pylab_setup
    globals(),locals(),[backend_name],0)
  File "/home/hakon/.pyenv/versions/3.6.1/lib/python3.6/site-packages/matplotlib/backends/backend_gtk3cairo.py", line 6, in 
    from . import backend_gtk3
  File "/home/hakon/.pyenv/versions/3.6.1/lib/python3.6/site-packages/matplotlib/backends/backend_gtk3.py", line 10, in 
    import gi
  File "/home/hakon/.pyenv/versions/3.6.1/lib/python3.6/site-packages/gi/__init__.py", line 39
    print url
            ^
SyntaxError: Missing parentheses in call to 'print'

Seems like pip somehow installed a Python 2 version? How can I fix this?

user_3926735 · Answer

The chosen answer is a little bit outdated as of now:

Last update of pgi in 2018
Since 2018, PyGObject is available for python3 from PyPI.

Installing the relevant package, plus its dependencies, depending on your environment, is still possible, just follow the steps from the doc.

But if you work from a venv, you might still stumble upon a ModuleNotFoundError: No module named 'gi' when importing gi. The venv ignores the system-wide module. Then simply run, from your venv: pip install PyGObject (or use poetry or your favorite python packages manager). Of course, you still need to have installed PyGObject's dependencies (see the link to the doc, right above).

user_3565696 · Answer

To install for the standard python, Håkon Hægland answer is the best choice.

But for an alternate python version, one can use pip. Beware that the alternate pip has to be used to match the alternate python.

The full explanations are given in the documentation.

For instance on openSUSE (standard python version 3.6, alternate installed 3.8):

> sudo zypper install cairo-devel pkg-config python3-devel gcc gobject-introspection-devel
> pip3.8 install --user pycairo
> pip3.8 install --user PyGObject
> python3.8
Python 3.8.1 (default, Feb  1 2020, 14:50:41) 
[GCC 7.5.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import gi
>>>

Python 3: Installing gi package with pip

3 Answers