[Bug]: Issue with find_nearest_contour in contour.py

[jhelmboldt]

Bug summary

The default for the indices keyword in the find_nearest_contour function within countour.py is defined incorrectly in the code. Line 1377 should be "indices = range(len(self.layers))" instead of "indices = range(len(self.levels))."

Code for reproduction

import numpy as np
import matplotlib.pyplot as plt
xy=np.indices((100,100))
img=np.exp(-np.pi*(np.sum((xy-50)**2,0)/20.**2))
cs=plt.contourf(img,50)
cs.find_nearest_contour(20,20,pixel=False)

Actual outcome

Traceback (most recent call last):
File "", line 1, in
File "/opt/local/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/matplotlib/contour.py", line 1388, in find_nearest_contour
con = self.collections[icon]
IndexError: list index out of range

Expected outcome

(0, 0, 397, 23.68976612821045, 14.034856810732212, 49.197307349357025)

Additional information

No response

Operating system

Mac OS 12.3.1

Matplotlib Version

3.5.1

Matplotlib Backend

TkAgg

Python version

3.8.12

Jupyter version

No response

Installation

pip

[tacaswell]

@jhelmboldt Would you be willing to open a PR with that change + a test?

[andrew-fennell]

If @jhelmboldt does not want to open a PR, I can make one later today.

[jhelmboldt]

Thanks, @andrew-fennell. I've never submitted a PR before and don't have time to learn today, so I would appreciate you handling it. Thank you.