[Bug]: Secondary axis does not accept python builtins for transform #22473
Description
Bug summary
The creation of a secondary axis is documented to accept a tuple of functions to create the transform between the two axes.
When created, it passes a numpy array to the declared functions, which may not accept the Type.
Code for reproduction
from matplotlib import pyplot as plt
from math import degrees, radians, pi
def deg2rad(x: float) -> float: return x/180*pi
def rad2deg(x: float) -> float: return x/pi*180
fig, ax = plt.subplots()
ax.plot([0, 1], [1, 0])
ax.secondary_xaxis('top', functions=(degrees, radians)) # Actual output
# ax.secondary_xaxis('top', functions=(deg2rad, rad2deg)) # Expected output
plt.show()Actual outcome
Exception in Tkinter callback
Traceback (most recent call last):
File "C:\Users\X\AppData\Local\Programs\Python\Python39\lib\tkinter\__init__.py", line 1892, in __call__
return self.func(*args)
File "C:\Users\X\AppData\Local\Programs\Python\Python39\lib\tkinter\__init__.py", line 814, in callit
func(*args)
File "C:\Users\X\Desktop\temp\.venv\lib\site-packages\matplotlib\backends\_backend_tk.py", line 240, in idle_draw
self.draw()
File "C:\Users\X\Desktop\temp\.venv\lib\site-packages\matplotlib\backends\backend_tkagg.py", line 9, in draw
super().draw()
File "C:\Users\X\Desktop\temp\.venv\lib\site-packages\matplotlib\backends\backend_agg.py", line 406, in draw
self.figure.draw(self.renderer)
File "C:\Users\X\Desktop\temp\.venv\lib\site-packages\matplotlib\artist.py", line 74, in draw_wrapper
result = draw(artist, renderer, *args, **kwargs)
File "C:\Users\X\Desktop\temp\.venv\lib\site-packages\matplotlib\artist.py", line 51, in draw_wrapper
return draw(artist, renderer, *args, **kwargs)
File "C:\Users\X\Desktop\temp\.venv\lib\site-packages\matplotlib\figure.py", line 2776, in draw
artists = self._get_draw_artists(renderer)
File "C:\Users\X\Desktop\temp\.venv\lib\site-packages\matplotlib\figure.py", line 247, in _get_draw_artists
child.apply_aspect(pos)
File "C:\Users\X\Desktop\temp\.venv\lib\site-packages\matplotlib\axes\_secondary_axes.py", line 123, in apply_aspect
self._set_lims()
File "C:\Users\X\Desktop\temp\.venv\lib\site-packages\matplotlib\axes\_secondary_axes.py", line 234, in _set_lims
lims = self._functions[0](np.array(lims))
TypeError: only size-1 arrays can be converted to Python scalars
Expected outcome
Additional information
Line 234 in _secondary_axes.py lims = self._functions[0](np.array(lims)) passes a numpy array to a function that may accept only floats.
Operating system
Windows
Matplotlib Version
3.5.1
Matplotlib Backend
TkAgg
Python version
3.9.2
Jupyter version
N/A
Installation
pip