Bug summary

If I create a figure with a radiobutton widget and then remove the radio widget axes in order to save the figure without the radiobutton box shown it throws an error in fig.savefig

Code for reproduction

importnumpyasnpimportmatplotlib.pyplotaspltfrommatplotlib.widgetsimportRadioButtons# data creationx=np.arange(0.0,3.0,0.01)y=np.sin(2*np.pi*x)# plotting datafig,ax=plt.subplots()l,=ax.plot(x,y)plt.subplots_adjust(left=0.3)# creating radio buttonsrax=plt.axes([0.05,0.5,0.15,0.30])radio=RadioButtons(rax,labels= ['red','blue','green'],active=2,activecolor='black')l.set_color(radio.value_selected)defcolor(label):l.set_color(label)fig.canvas.draw()radio.on_clicked(color)plt.show()# remove radio buttons axesradio.ax.remove()fig.tight_layout()fig.savefig('figure.png')

Actual outcome

Traceback (most recent call last):
File "/nfs/chess/user/rv43/miniforge3/envs/CHAP_tomo/lib/python3.10/site-packages/matplotlib/cbook.py", line 298, in process
func(*args, **kwargs)
File "/nfs/chess/user/rv43/miniforge3/envs/CHAP_tomo/lib/python3.10/site-packages/matplotlib/widgets.py", line 1665, in _clear
if self.ignore(event) or self.canvas.is_saving():
File "/nfs/chess/user/rv43/miniforge3/envs/CHAP_tomo/lib/python3.10/site-packages/matplotlib/widgets.py", line 120, in
canvas = property(lambda self: self.ax.figure.canvas)
AttributeError: 'NoneType' object has no attribute 'canvas'
Traceback (most recent call last):
File "/nfs/chess/user/rv43/miniforge3/envs/CHAP_tomo/lib/python3.10/site-packages/matplotlib/cbook.py", line 298, in process
func(*args, **kwargs)
File "/nfs/chess/user/rv43/miniforge3/envs/CHAP_tomo/lib/python3.10/site-packages/matplotlib/widgets.py", line 1665, in _clear
if self.ignore(event) or self.canvas.is_saving():
File "/nfs/chess/user/rv43/miniforge3/envs/CHAP_tomo/lib/python3.10/site-packages/matplotlib/widgets.py", line 120, in
canvas = property(lambda self: self.ax.figure.canvas)
AttributeError: 'NoneType' object has no attribute 'canvas'

Expected outcome

This example does produce the correct figure (one with a tight layout and no radiobuttons box), since the error that is thrown is caught by matplotlib and only printed as a warning.

Additional information

In matplotlib/widgets.py:
Replacing:
def _clear(self, event):
"""Internal event handler to clear the buttons."""
if self.ignore(event) or self.canvas.is_saving():
return
self._background = self.canvas.copy_from_bbox(self.ax.bbox)
self.ax.draw_artist(self._buttons)
With:
def _clear(self, event):
"""Internal event handler to clear the buttons."""
if self.ax._stale or self.ignore(event) or self.canvas.is_saving():
return
self._background = self.canvas.copy_from_bbox(self.ax.bbox)
self.ax.draw_artist(self._buttons)
Suppresses the issue, but I'm not sure if that is the desired fix or if self.ax._stale has another purpose. I have not tested CheckButtons widgets, but I'm wondering if the same happens there.

It may be wrapped up in self.ignore(event) by setting self.active = False when the radiobuttons get removed, but I don't know if that has other side effects.

Operating system

Scientific Linux 7, AlmaLinux-9

Matplotlib Version

3.9.2, 3.10.3

Matplotlib Backend

qtagg

Python version

3.10.18

Jupyter version

N/A

Installation

conda