Bug report

Bug summary

pcolor() produces a deprecation warning with default settings.

The default ofrcParams['pcolor.shading'] seems to be'flat', which is deprecated (at least sometimes). Maybe the default should be changed to'auto' or'nearest'?

Code for reproduction

frommatplotlibimportpyplotaspltimportnumpyasnpx=np.arange(2.)y=np.arange(2.)z=np.ones([2,2])plt.pcolor(x,y,z)

Actual outcome

MatplotlibDeprecationWarning: shading='flat' when X and Y have the same dimensions as C is deprecated since 3.3.  Either specify the corners of the quadrilaterals with X and Y, or pass shading='auto', 'nearest' or 'gouraud', or set rcParams['pcolor.shading'].  This will become an error two minor releases later.  plt.pcolor(x,y,z)

Expected outcome

No warning

Matplotlib version

• Operating system: Linux Mint 19
• Matplotlib version: 3.3.2
• Matplotlib backend (print(matplotlib.get_backend())): Qt5Agg
• Python version: 3.7.6
• Jupyter version (if applicable): N/A
• Other libraries: None

Installed with conda from conda-forge