[Bug]: plt.clabel raises exception at very low DPI: ValueError: 'codes' must be a 1D list or array with the same length of 'vertices'. Your vertices have shape (2, 2) but your codes have shape (1,) #26971
Description
Bug summary
This worked up to and including Matplotlib 3.7.3 and broke in Matplotlib 3.8.0.
Data files for sample code below:
x.txt
y.txt
z.txt
Code for reproduction
import matplotlib
matplotlib.rcParams['figure.dpi'] = matplotlib.rcParams['savefig.dpi'] = 4
from matplotlib import pyplot as plt
import numpy as np
# See data files attached above: x.txt, y.txt, z.txt
x = np.loadtxt('x.txt')
y = np.loadtxt('y.txt')
z = np.loadtxt('z.txt')
ax = plt.axes()
contourset = ax.contour(x, y, z, levels=[90.0], linewidths=0.5)
ax.clabel(contourset)
plt.savefig('test.pdf')Actual outcome
Traceback (most recent call last):
File "/private/tmp/test.py", line 13, in <module>
ax.clabel(contourset)
File "/Users/lpsinger/Library/Python/3.11/lib/python/site-packages/matplotlib/axes/_axes.py", line 6550, in clabel
return CS.clabel(levels, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/lpsinger/Library/Python/3.11/lib/python/site-packages/matplotlib/contour.py", line 222, in clabel
self.labels(inline, inline_spacing)
File "/Users/lpsinger/Library/Python/3.11/lib/python/site-packages/matplotlib/contour.py", line 622, in labels
rotation, path = self._split_path_and_get_label_rotation(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/lpsinger/Library/Python/3.11/lib/python/site-packages/matplotlib/contour.py", line 436, in _split_path_and_get_label_rotation
return angle, Path(xys, codes)
^^^^^^^^^^^^^^^^
File "/Users/lpsinger/Library/Python/3.11/lib/python/site-packages/matplotlib/path.py", line 135, in __init__
raise ValueError("'codes' must be a 1D list or array with the "
ValueError: 'codes' must be a 1D list or array with the same length of 'vertices'. Your vertices have shape (2, 2) but your codes have shape (1,)
Expected outcome
Additional information
I discovered this regression in the CI pipeline from one of my own projects, in a test that sets DPI to an extremely low value for performance purposes. https://git.ligo.org/lscsoft/ligo.skymap/-/jobs/2961694
Operating system
macOS
Matplotlib Version
3.8.0
Matplotlib Backend
MacOSX
Python version
3.11.5
Jupyter version
N/A
Installation
pip