Matplotlib deprecation warnings

[poplarShift]

import geoviews as gv
gv.extension('matplotlib')
gv.Points([])

is currently returning

_collections_abc.py:832: MatplotlibDeprecationWarning: 
The datapath rcparam was deprecated in Matplotlib 3.2.1 and will be removed two minor releases later.
  self[key] = other[key]

[mc51]

I can confirm this with this env: https://pastebin.com/TF28BgUz
and conda:

     active environment : geo2
    active env location : \Software\Anaconda3\envs\geo2
            shell level : 1
          conda version : 4.8.3
    conda-build version : 3.18.7
         python version : 3.6.8.final.0
       virtual packages :
       base environment : \Software\Anaconda3  (writable)
           channel URLs : https://conda.anaconda.org/pyviz/win-64
                          https://conda.anaconda.org/pyviz/noarch
                          https://conda.anaconda.org/conda-forge/win-64
                          https://conda.anaconda.org/conda-forge/noarch
                          https://repo.anaconda.com/pkgs/main/win-64
                          https://repo.anaconda.com/pkgs/main/noarch
                          https://repo.anaconda.com/pkgs/r/win-64
                          https://repo.anaconda.com/pkgs/r/noarch
                          https://repo.anaconda.com/pkgs/msys2/win-64
                          https://repo.anaconda.com/pkgs/msys2/noarch
               platform : win-64
             user-agent : conda/4.8.3 requests/2.23.0 CPython/3.6.8 Windows/10 Windows/10.0.16299
          administrator : False
             netrc file : None
           offline mode : False

[philippjfr]

Weird, anyone have an idea what's triggering these? I'm not aware of anywhere in GeoViews that sets rcparams but may be wrong.

[poplarShift]

Hah, nevermind. It's already in holoviews, no idea why I hadn't noticed it there before, thought I'd checked. Can you transfer this issue?

(Is this holoviz/holoviews#3766 coming back from the dead or did we simply never get rid of it?)

[philippjfr]

I've not seen these warnings in HoloViews anymore. Could this be a cartopy issue?

[philippjfr]

Easiest thing to do is probably just to stick a import traceback as tb; tb.print_stack() into the matplotlib file from where the warning is being raised.

[poplarShift]

Nope, it's definitely there in holoviews but you might have to force mpl to 3.2.1 (not 3.2.0).

https://matplotlib.org/3.2.1/api/prev_api_changes/api_changes_3.2.0.html#the-datapath-rcparam