pull_requests: 625489541

This data as json

id node_id number state locked title user body created_at updated_at closed_at merged_at merge_commit_sha assignee milestone draft head base author_association auto_merge repo url merged_by
625489541 MDExOlB1bGxSZXF1ZXN0NjI1NDg5NTQx 5231 closed 0 open_mfdataset: Raise if combine='by_coords' and concat_dim=None 35968931 Fixes bug which allowed incorrect arguments to be passed to `open_mfdataset` without complaint. The combination `open_mfdataset(files, combine='by_coords', concat_dim='t')` should never have been permitted, and in fact it [wasn't permitted](https://github.com/pydata/xarray/blob/795926a50c690cae20e928f2514b2269f09a9b91/xarray/core/combine.py#L597) until the last part of the deprecation process from the old `auto_combine`. It makes no sense to pass this combination because the `combine_by_coords` function does not have a `concat_dim` argument at all! The effect was pretty benign - the `concat_dim` arg wasn't really used for anything in that case, and the result of passing dodgy datasets would just be a less informative error. However there were multiple tests which assumed this behaviour was okay - I had to remove that particular parametrization for a bunch of your join tests @dcherian because they now fail with a different (clearer) error. I also noticed a related issue which I fixed - internally `open_mfdataset` was performing a rearrangement of the input datasets that it needs for the case `combine='nested'`, even in the case `combine='by_coords'`. I hadn't previously realised that we can just skip this rearrangement without issue, so `open_mfdataset(combine='by_coords')` should be a little bit faster now. - [x] Closes #5230 - [x] Tests added - [x] Passes `pre-commit run --all-files` - [x] User visible changes (including notable bug fixes) are documented in `whats-new.rst` 2021-04-28T19:16:19Z 2021-04-30T12:41:17Z 2021-04-30T12:41:17Z 2021-04-30T12:41:17Z 01b6cc76c6b7c77f2f93fc1766eb76f851529b5d     0 07d8ec01ef01b196e3f1d198da99c3d198e60148 0021cdab91f7466f4be0fb32dae92bf3f8290e19 MEMBER   13221727 https://github.com/pydata/xarray/pull/5231  

Links from other tables