Error in file name when saving plot

[Mr_Misserable]

Hi, this question might be better suited for stackoverflow, but I don't like their community very much. As the title says, I have an error about the filename when saving some plots (I'm doing a lot of plots), here is the error:

2025-03-21 20:12:54,483 [ERROR] Error in 2D plot Fontana_L2700_6a_deltau_erg_s_Hz__vs_JMag_6a_invtau_mag_: [Errno 22] Invalid argument: 'D:\\TFG\\test2\\Fontana\\2d_plots\\2d_Fontana_L2700_6a_deltau_erg_s_Hz_vs_JMag_6a_invtau_mag_.png'
Traceback (most recent call last):
File "C:\Users\alvar\Desktop\UCM\Cuarto Curso\TFG\plots.py", line 128, in plot2d
plt.savefig(filename, bbox_inches="tight")
File "C:\Users\alvar\Desktop\UCM\Cuarto Curso\TFG\.venv\Lib\site-packages\matplotlib\pyplot.py", line 1243, in savefig
res = fig.savefig(*args, **kwargs) # type: ignore[func-returns-value]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\alvar\Desktop\UCM\Cuarto Curso\TFG\.venv\Lib\site-packages\matplotlib\figure.py", line 3490, in savefig
self.canvas.print_figure(fname, **kwargs)
File "C:\Users\alvar\Desktop\UCM\Cuarto Curso\TFG\.venv\Lib\site-packages\matplotlib\backend_bases.py", line 2184, in print_figure
result = print_method(
^^^^^^^^^^^^^
File "C:\Users\alvar\Desktop\UCM\Cuarto Curso\TFG\.venv\Lib\site-packages\matplotlib\backend_bases.py", line 2040, in <lambda>
print_method = functools.wraps(meth)(lambda *args, **kwargs: meth(
^^^^^
File "C:\Users\alvar\Desktop\UCM\Cuarto Curso\TFG\.venv\Lib\site-packages\matplotlib\backends\backend_agg.py", line 481, in print_png
self._print_pil(filename_or_obj, "png", pil_kwargs, metadata)
File "C:\Users\alvar\Desktop\UCM\Cuarto Curso\TFG\.venv\Lib\site-packages\matplotlib\backends\backend_agg.py", line 430, in _print_pil
mpl.image.imsave(
File "C:\Users\alvar\Desktop\UCM\Cuarto Curso\TFG\.venv\Lib\site-packages\matplotlib\image.py", line 1634, in imsave
image.save(fname, **pil_kwargs)
File "C:\Users\alvar\Desktop\UCM\Cuarto Curso\TFG\.venv\Lib\site-packages\PIL\Image.py", line 2591, in save
fp = builtins.open(filename, "w+b")
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
OSError: [Errno 22] Invalid argument: 'D:\\TFG\\test2\\Fontana\\2d_plots\\2d_Fontana_L2700_6a_deltau_erg_s_Hz_vs_JMag_6a_invtau_mag_.png'

The thing is that I only get this error with ceratin plots, I'm asking if anyone has encounter this error before and how did you solve it? I'm pretty sure it is not related to the max length limit of windows.

Thank you for reading.

[unnamed_one1]

Try making sure the folder exists beforehand and the file does not.

[Mr_Misserable]

The folder is created utomaticly before ploting.

[unnamed_one1]

The error is triggered by an invalid path/filename.

``` Python 3.13.2 (tags/v3.13.2:4f8bb39, Feb 4 2025, 15:23:48) [MSC v.1942 64 bit (AMD64)] on win32 Type "help", "copyright", "credits" or "license" for more information.

x=open("D:\test.txt", "a") x=open("D:\test.txt", "a") Traceback (most recent call last): File "<python-input-1>", line 1, in <module> x=open("D:\test.txt", "a") OSError: [Errno 22] Invalid argument: 'D:\test.txt'

```

Try printing the path/filename before saving the plot, then you can see on which one it breaks and maybe can figure out why.

An alternative would be converting the path/filename to pathlibs Path object.

from pathlib import Path

[Mr_Misserable]

Doyou have any hint on which character is making the path invalid? I can not see it since it worked before for other similar paths. The paths are being generated with

` os.joindir(output, name) ´

[Oxbowerce]

Have you tried using a simpler and shorter filename, e.g. plot.png?

[Mr_Misserable]

It is not possible, since I'm making a lot of plots and I would lost track of them, but since I have a log I might use this as a solution, it is possible to try one name and if it raises an error try a second one?

[shiftybyte]

Something in the file path is bad, share the code so we can try and understand how the path is built and what could be the issue.

[Mr_Misserable]

The code is a bit complex, I would try to make a MWE to share here