Closed
Description
Bug summary
With the recent mpl prerelease, we started to have a failure in the test suite of nilearn, a package that depends on matplotlib for visualization. I reproduced the error with a matplotlib example and it seems that when calling Axes.contours it's not possible to set the levels parameter to values less than vmin using array-like input. This happens even when vmax is also set by the user and it seems to be because vmax ends up being set to 0 internally. The code reproduced below will throw ValueError: minvalue must be less than or equal to maxvalue. I'm not sure if it's a usage error or a bug so let me know if this is expected behavior, however as I understand it the values for levels and vmin and vmax should be independent.
Code for reproduction
import matplotlib.pyplot as plt
import numpy as np
feature_x = np.arange(0, 50, 2)
feature_y = np.arange(0, 50, 3)
# Creating 2-D grid of features
[X, Y] = np.meshgrid(feature_x, feature_y)
fig, ax = plt.subplots(1, 1)
Z = np.cos(X / 2) + np.sin(Y / 4)
# plots contour lines
ax.contour(X, Y, Z, levels=[0.0, 0.1], vmin=0.2, vmax=0.8)Actual outcome
ValueError Traceback (most recent call last)
[/home/yasmin/.config/Code/User/globalStorage/buenon.scratchpads/scratchpads/47a6066b9dfaca1c2b13ea2e99f4e929/scratch.py](https://file+.vscode-resource.vscode-cdn.net/home/yasmin/.config/Code/User/globalStorage/buenon.scratchpads/scratchpads/47a6066b9dfaca1c2b13ea2e99f4e929/scratch.py) in ()
[109](file:///home/yasmin/.config/Code/User/globalStorage/buenon.scratchpads/scratchpads/47a6066b9dfaca1c2b13ea2e99f4e929/scratch.py?line=108) Z = np.cos(X [/](https://file+.vscode-resource.vscode-cdn.net/) 2) + np.sin(Y [/](https://file+.vscode-resource.vscode-cdn.net/) 4)
[111](file:///home/yasmin/.config/Code/User/globalStorage/buenon.scratchpads/scratchpads/47a6066b9dfaca1c2b13ea2e99f4e929/scratch.py?line=110) # plots contour lines
---> [112](file:///home/yasmin/.config/Code/User/globalStorage/buenon.scratchpads/scratchpads/47a6066b9dfaca1c2b13ea2e99f4e929/scratch.py?line=111) ax.contour(X, Y, Z, levels=[0.0, 0.1], vmin=0.2, vmax=0.8)
File [~/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/__init__.py:1465](https://file+.vscode-resource.vscode-cdn.net/home/yasmin/nilearn/nilearn/~/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/__init__.py:1465), in _preprocess_data..inner(ax, data, *args, **kwargs)
[1462](file:///home/yasmin/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/__init__.py?line=1461) @functools.wraps(func)
[1463](file:///home/yasmin/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/__init__.py?line=1462) def inner(ax, *args, data=None, **kwargs):
[1464](file:///home/yasmin/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/__init__.py?line=1463) if data is None:
-> [1465](file:///home/yasmin/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/__init__.py?line=1464) return func(ax, *map(sanitize_sequence, args), **kwargs)
[1467](file:///home/yasmin/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/__init__.py?line=1466) bound = new_sig.bind(ax, *args, **kwargs)
[1468](file:///home/yasmin/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/__init__.py?line=1467) auto_label = (bound.arguments.get(label_namer)
[1469](file:///home/yasmin/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/__init__.py?line=1468) or bound.kwargs.get(label_namer))
File [~/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/axes/_axes.py:6498](https://file+.vscode-resource.vscode-cdn.net/home/yasmin/nilearn/nilearn/~/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/axes/_axes.py:6498), in Axes.contour(self, *args, **kwargs)
[6489](file:///home/yasmin/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/axes/_axes.py?line=6488) """
[6490](file:///home/yasmin/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/axes/_axes.py?line=6489) Plot contour lines.
[6491](file:///home/yasmin/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/axes/_axes.py?line=6490)
(...)
[6495](file:///home/yasmin/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/axes/_axes.py?line=6494) %(contour_doc)s
[6496](file:///home/yasmin/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/axes/_axes.py?line=6495) """
[6497](file:///home/yasmin/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/axes/_axes.py?line=6496) kwargs['filled'] = False
-> [6498](file:///home/yasmin/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/axes/_axes.py?line=6497) contours = mcontour.QuadContourSet(self, *args, **kwargs)
...
-> [1361](file:///home/yasmin/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/colors.py?line=1360) raise ValueError("minvalue must be less than or equal to maxvalue")
[1362](file:///home/yasmin/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/colors.py?line=1361) else:
[1363](file:///home/yasmin/miniconda3/envs/nilearn-dev/lib/python3.10/site-packages/matplotlib/colors.py?line=1362) if clip:
ValueError: minvalue must be less than or equal to maxvalueExpected outcome
A plot matplotlib.contour.QuadContourSet object
Additional information
The test that led to this failure did pass before this version
Operating system
Ubuntu 22.04
Matplotlib Version
3.8.0rc1
Matplotlib Backend
module://matplotlib_inline.backend_inline
Python version
3.10.4
Jupyter version
No response
Installation
pip