html_url,issue_url,id,node_id,user,created_at,updated_at,author_association,body,reactions,performed_via_github_app,issue
https://github.com/pydata/xarray/issues/4596#issuecomment-750402407,https://api.github.com/repos/pydata/xarray/issues/4596,750402407,MDEyOklzc3VlQ29tbWVudDc1MDQwMjQwNw==,10194086,2020-12-23T17:37:07Z,2020-12-23T17:37:07Z,MEMBER,"> I could not find anything about mpl removing flat shading, are you sure about that?

It's in the deprecation warning: `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.`

> I believe the best (albeit tedious) solution is to resample the coordinates from nxny to (nx+1)(ny+1)

We are currently doing this (if the coordinates are monotonic). And mpl also started doing it (and now gives a warning on non-monotonic coordinates). The problem is that with non-monotonic coordinates it leads to wrong results.

> If only needs to be ensured that none of the 'new' quadliterals crosses the map boundary.

I think that's not trivial - see also: SciTools/cartopy#1638 and matplotlib/matplotlib#18317 and has to be fixed upstream. There is a proposed fix, see: SciTools/cartopy#1646.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,746929580
https://github.com/pydata/xarray/issues/4596#issuecomment-730698059,https://api.github.com/repos/pydata/xarray/issues/4596,730698059,MDEyOklzc3VlQ29tbWVudDczMDY5ODA1OQ==,10194086,2020-11-19T23:18:23Z,2020-11-19T23:18:23Z,MEMBER,"Yes, this is due to an upstream change in matplotlib - see also #4364. mpl tries to infer the edges of the gridcell - which does not work if the data is not monotonic. In the short term we can fix this by passing `shading=""flat""`:

```python
ds.Tair[0].plot.pcolormesh(ax=ax, transform=ccrs.PlateCarree(), x='xc', y='yc', add_colorbar=False)
```

however, mpl will eventually remove `shading=""flat""`. I am not sure what the best way forward is. mpl recommends to drop a row and column of the data (which it did earlier automatically). See:

https://github.com/SciTools/cartopy/issues/1638#issuecomment-692741908","{""total_count"": 1, ""+1"": 1, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,746929580