importmatplotlib.pyplotaspltimportnumpyasnpfrommatplotlibimportcolorsnp.random.seed(19680801)data=np.random.rand(10,20)fig,ax=plt.subplots()norm=colors.Normalize(vmin=np.max(data),vmax=np.min(data))im=ax.imshow(data,norm=norm)plt.show()

Traceback (most recent call last):  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/backends/backend_qt.py", line 498, in _draw_idle    self.draw()  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/backends/backend_agg.py", line 387, in draw    self.figure.draw(self.renderer)  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/artist.py", line 95, in draw_wrapper    result = draw(artist, renderer, *args, **kwargs)  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/artist.py", line 72, in draw_wrapper    return draw(artist, renderer)  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/figure.py", line 3224, in draw    mimage._draw_list_compositing_images(  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/image.py", line 132, in _draw_list_compositing_images    a.draw(renderer)  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/artist.py", line 72, in draw_wrapper    return draw(artist, renderer)  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/axes/_base.py", line 3152, in draw    mimage._draw_list_compositing_images(  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/image.py", line 132, in _draw_list_compositing_images    a.draw(renderer)  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/artist.py", line 72, in draw_wrapper    return draw(artist, renderer)  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/image.py", line 651, in draw    im, l, b, trans = self.make_image(  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/image.py", line 950, in make_image    return self._make_image(self._A, bbox, transformed_bbox, clip,  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/image.py", line 551, in _make_image    output = self.norm(resampled_masked)  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/colors.py", line 1395, in __call__    raise ValueError("minvalue must be less than or equal to maxvalue")ValueError: minvalue must be less than or equal to maxvalue

Exception in Tkinter callbackTraceback (most recent call last):  File "/home/ruth/miniforge3/envs/mpl-dev/lib/python3.9/tkinter/__init__.py", line 1892, in __call__    return self.func(*args)  File "/home/ruth/miniforge3/envs/mpl-dev/lib/python3.9/tkinter/__init__.py", line 814, in callit    func(*args)  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/backends/_backend_tk.py", line 271, in idle_draw    self.draw()  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/backends/backend_tkagg.py", line 10, in draw    super().draw()  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/backends/backend_agg.py", line 387, in draw    self.figure.draw(self.renderer)  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/artist.py", line 95, in draw_wrapper    result = draw(artist, renderer, *args, **kwargs)  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/artist.py", line 72, in draw_wrapper    return draw(artist, renderer)  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/figure.py", line 3224, in draw    mimage._draw_list_compositing_images(  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/image.py", line 132, in _draw_list_compositing_images    a.draw(renderer)  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/artist.py", line 72, in draw_wrapper    return draw(artist, renderer)  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/axes/_base.py", line 3152, in draw    mimage._draw_list_compositing_images(  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/image.py", line 132, in _draw_list_compositing_images    a.draw(renderer)  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/artist.py", line 72, in draw_wrapper    return draw(artist, renderer)  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/image.py", line 651, in draw    im, l, b, trans = self.make_image(  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/image.py", line 950, in make_image    return self._make_image(self._A, bbox, transformed_bbox, clip,  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/image.py", line 551, in _make_image    output = self.norm(resampled_masked)  File "/home/ruth/git_stuff/matplotlib/lib/matplotlib/colors.py", line 1395, in __call__    raise ValueError("minvalue must be less than or equal to maxvalue")ValueError: minvalue must be less than or equal to maxvalue