首先，pip install gi将安装另一个不相关的软件包，正确的名称是pgi。但运行后：

$ pip uninstall gi
$ pip install pgi
$ python toolmanager.py
[...]
Traceback (most recent call last):
  File "toolmanager.py", line 14, in <module>
    import matplotlib.pyplot as plt
  File "/home/hakon/.pyenv/versions/3.6.1/lib/python3.6/site-packages/matplotlib/pyplot.py", line 115, in <module>
    _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 <module>
    from . import backend_gtk3
  File "/home/hakon/.pyenv/versions/3.6.1/lib/python3.6/site-packages/matplotlib/backends/backend_gtk3.py", line 12, in <module>
    raise ImportError("Gtk3 backend requires pygobject to be installed.")
ImportError: Gtk3 backend requires pygobject to be installed.

Python 3的pygobject似乎不能从PyPI安装。所以我尝试从Ubuntu分发包python3-gi安装所有内容：

$ sudo apt-get install python3-gi
$ pyenv local system
$ python3 --version
Python 3.5.3
$ python3 toolmanager.py

这个很好用：）

chosen answer现在有点过时了：

• 最后更新pgi在2018
• 自2018年以来，PyGObject可用于PyPI的Python 3。

根据您的环境，仍然可以安装相关的软件包及其依赖项，只需遵循steps from the doc。
但是如果你使用venv，在导入gi时，你仍然可能会遇到ModuleNotFoundError: No module named 'gi'。venv会忽略系统范围的模块。然后简单地运行，从你的venv：pip install PyGObject（或者使用poetry或你喜欢的python包管理器）。当然，你仍然需要安装PyGObject的依赖项（参见上面的文档链接）。

要安装标准python，Håkon Hægland answer是最佳选择。
但是对于alternate python version，可以使用pip<version>。注意，必须使用备用pip来匹配备用python。
文件中给出了完整的解释。
例如在openSUSE上（标准python版本3.6，备用安装版本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
>>>

我在使用gradio应用程序时遇到了同样的问题。解决方案

Running on local URL:  http://127.0.0.1:7860

To create a public link, set `share=True` in `launch()`.
Traceback (most recent call last):
  File "/home/pi/env/lib/python3.9/site-packages/gradio/routes.py", line 508, in predict
    output = await route_utils.call_process_api(
  File "/home/pi/env/lib/python3.9/site-packages/gradio/route_utils.py", line 218, in call_process_api
    with utils.MatplotlibBackendMananger():
  File "/home/pi/env/lib/python3.9/site-packages/gradio/utils.py", line 817, in __enter__
    self._original_backend = matplotlib.get_backend()
  File "/home/pi/env/lib/python3.9/site-packages/matplotlib/__init__.py", line 1275, in get_backend
    return rcParams['backend']
  File "/home/pi/env/lib/python3.9/site-packages/matplotlib/__init__.py", line 760, in __getitem__
    plt.switch_backend(rcsetup._auto_backend_sentinel)
  File "/home/pi/env/lib/python3.9/site-packages/matplotlib/pyplot.py", line 327, in switch_backend
    switch_backend(candidate)
  File "/home/pi/env/lib/python3.9/site-packages/matplotlib/pyplot.py", line 342, in switch_backend
    module = importlib.import_module(cbook._backend_module_name(newbackend))
  File "/usr/lib/python3.9/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
  File "<frozen importlib._bootstrap>", line 986, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 680, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 790, in exec_module
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File "/home/pi/env/lib/python3.9/site-packages/matplotlib/backends/backend_gtk4agg.py", line 4, in <module>
    from . import backend_agg, backend_gtk4
  File "/home/pi/env/lib/python3.9/site-packages/matplotlib/backends/backend_gtk4.py", line 12, in <module>
    import gi
  File "/home/pi/env/lib/python3.9/site-packages/gi/__init__.py", line 39
            print url
                  ^
SyntaxError: Missing parentheses in call to 'print'. Did you mean print(url)?

pip uninstall gi pip3 install pgi
对我很有效