Python scripts based on matplotlib do not work anymore

[angelog0]

My scripts based on matplotlib do not work anymore. For example the following code

import matplotlib.pyplot as plt

x = 0.74
y = 3.5

plt.plot([1,2,3,4])

plt.plot(x,y,marker='o',color='red')

plt.show()

now produces these errors:

$ python3 pltdemo.py
Traceback (most recent call last):
  File "C:/msys64/home/utente/py.apps/pltdemo.py", line 22, in <module>
    plt.plot([1,2,3,4])
  File "C:/msys64/mingw64/lib/python3.11/site-packages/matplotlib/pyplot.py", line 3578, in plot
    return gca().plot(
           ^^^^^
  File "C:/msys64/mingw64/lib/python3.11/site-packages/matplotlib/pyplot.py", line 2528, in gca
    return gcf().gca()
           ^^^^^
  File "C:/msys64/mingw64/lib/python3.11/site-packages/matplotlib/pyplot.py", line 1000, in gcf
    return figure()
           ^^^^^^^^
  File "C:/msys64/mingw64/lib/python3.11/site-packages/matplotlib/pyplot.py", line 934, in figure
    manager = new_figure_manager(
              ^^^^^^^^^^^^^^^^^^^
  File "C:/msys64/mingw64/lib/python3.11/site-packages/matplotlib/pyplot.py", line 464, in new_figure_manager
    _warn_if_gui_out_of_main_thread()
  File "C:/msys64/mingw64/lib/python3.11/site-packages/matplotlib/pyplot.py", line 441, in _warn_if_gui_out_of_main_thread
    canvas_class = cast(type[FigureCanvasBase], _get_backend_mod().FigureCanvas)
                                                ^^^^^^^^^^^^^^^^^^
  File "C:/msys64/mingw64/lib/python3.11/site-packages/matplotlib/pyplot.py", line 280, in _get_backend_mod
    switch_backend(rcParams._get("backend"))  # type: ignore[attr-defined]
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:/msys64/mingw64/lib/python3.11/site-packages/matplotlib/pyplot.py", line 327, in switch_backend
    switch_backend(candidate)
  File "C:/msys64/mingw64/lib/python3.11/site-packages/matplotlib/pyplot.py", line 342, in switch_backend
    module = importlib.import_module(cbook._backend_module_name(newbackend))
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:/msys64/mingw64/lib/python3.11/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen importlib._bootstrap>", line 1204, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1176, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1147, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 690, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 944, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "C:/msys64/mingw64/lib/python3.11/site-packages/matplotlib/backends/backend_gtk4agg.py", line 4, in <module>
    from . import backend_agg, backend_gtk4
  File "C:/msys64/mingw64/lib/python3.11/site-packages/matplotlib/backends/backend_gtk4.py", line 19, in <module>
    gi.require_version("Gtk", "4.0")
    ^^^^^^^^^^^^^^^^^^
AttributeError: module 'gi' has no attribute 'require_version'

The same code works in WSL and it was working until a few months ago on MSYS2/MINGW64

• [X] I have verified that my MSYS2 is up-to-date before submitting the report (see https://www.msys2.org/docs/updating/)

Windows Version

MINGW64_NT-10.0-19045

MINGW environments affected

• [X] MINGW64
• [ ] MINGW32
• [ ] UCRT64
• [ ] CLANG64
• [ ] CLANG32
• [ ] CLANGARM64

Are you willing to submit a PR?

No response

[Biswa96]

I can not reproduce the issue in my system. I have installed python-matplotlib in clean mingw64 environment and your given python script shows a diagonal plot with a red dot.

[angelog0]

@Biswa96, you do not say on which OS...

[Biswa96]

I am using Microsoft Windows Version 10.0.19045.xxxx

[angelog0]

Maybe I have found the culprit. It is the installation of the GIMP package (both in MINGW64 and UCRT64) which breaks things. After uninstalling it with pacman -Rscn ... , things start to work again.

I wonder if this is caused by the fact that installing GIMP installs pyton2, gtk2 etc..

[angelog0]

It seems that installing GIMP3 works better...

[Biswa96]

So, nothing to solve, right?

[angelog0]

The GIMP package conflicts with Python3. GIMP3 fixes things.

Maybe you should rename

• GIMP --> GIMP2 and declare it in conflict with PYTHON3 (who installs PYTHON3 cannot install GIMP2 and viceversa)
• GIMP3 --> GIMP

[MehdiChinoune]

The GIMP package conflicts with Python3. GIMP3 fixes things.

Maybe you should rename

• GIMP --> GIMP2 and declare it in conflict with PYTHON3 (who installs PYTHON3 cannot install GIMP2 and viceversa)
• GIMP3 --> GIMP

We couldn't because gimp3 is not stable (officially) yet, wait until stable release.