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/pull/6795#issuecomment-1276433539,https://api.github.com/repos/pydata/xarray/issues/6795,1276433539,IC_kwDOAMm_X85MFNSD,4160723,2022-10-12T16:19:34Z,2022-10-12T16:19:34Z,MEMBER,"Looks good to me @keewis. Thanks for your work on the indexes repr!

Yes I think we can skip displaying default indexes for now... The question is which indexes are considered as default, i.e., all `PandasIndex` and `PandasMultiIndex` instances (like in this PR) or just the single pandas indexes automatically created for the dimension coordinates? We can decide this later, though, it's not a problem adding more indexes in the text repr later (we'll probably need it when dropping the multi-index dimension coordinate with tuple elements). For the html repr it's easier: we could display all indexes and collapse the section by default.

> but I thought ""dimension coordinates"" (and in particular their indexes) are still used for alignment?

Yes that's a good point. Let's keep ""dimensions without coordinates"".","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1306887842
https://github.com/pydata/xarray/pull/6795#issuecomment-1266702407,https://api.github.com/repos/pydata/xarray/issues/6795,1266702407,IC_kwDOAMm_X85LgFhH,14808389,2022-10-04T09:59:29Z,2022-10-04T15:28:25Z,MEMBER,"not really, I wanted to wait until `set_xindex` was in main (the PR has been merged last week) and have not looked at it since.

Edit: we don't yet have tests, though

There's two issues left that might need a bit of discussion: in [8f21df3](https://github.com/pydata/xarray/pull/6795/commits/8f21df36e22d996bb436f87df1a3257da6015c47) I skipped displaying default `PandasIndex` instances because that's basically redundant with the `*` on coordinates (and it would have required me to update a lot of doctests, which will probably make this a breaking change). If we decide to revert that, should we mark every coordinate with an index with a `*`?

Another proposal we had was to replace the ""dimensions without coordinates"" line with a ""coordinates without index"" line. @benbovy, this might be a misunderstanding on my part, but I thought ""dimension coordinates"" (and in particular their indexes) are still used for alignment? If so, I think we might need both lines.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1306887842
https://github.com/pydata/xarray/pull/6795#issuecomment-1266033247,https://api.github.com/repos/pydata/xarray/issues/6795,1266033247,IC_kwDOAMm_X85LdiJf,2448579,2022-10-03T20:52:24Z,2022-10-03T20:52:24Z,MEMBER,"I think we should move forward here.

Are there any real blockers?","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1306887842
https://github.com/pydata/xarray/pull/6795#issuecomment-1248532873,https://api.github.com/repos/pydata/xarray/issues/6795,1248532873,IC_kwDOAMm_X85KaxmJ,35968931,2022-09-15T19:41:01Z,2022-09-15T19:41:01Z,MEMBER,"> should we skip PandasIndex and PandasMultiIndex?

If we're [encouraging people to look at these / subclass them](https://github.com/pydata/xarray/issues/7031#issuecomment-1248259720) to create custom indexes, then they should have a repr too.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1306887842
https://github.com/pydata/xarray/pull/6795#issuecomment-1202548224,https://api.github.com/repos/pydata/xarray/issues/6795,1202548224,IC_kwDOAMm_X85HrW4A,4160723,2022-08-02T13:22:24Z,2022-08-02T13:22:24Z,MEMBER,"From #6867 (https://github.com/pydata/xarray/issues/6867#issuecomment-1202535745), we might want to update the ""Dimensions without coordinates"" line too.  ","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1306887842
https://github.com/pydata/xarray/pull/6795#issuecomment-1196967258,https://api.github.com/repos/pydata/xarray/issues/6795,1196967258,IC_kwDOAMm_X85HWEVa,2448579,2022-07-27T16:15:57Z,2022-07-27T16:15:57Z,MEMBER,Shall we point this at the `main` branch instead?,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1306887842
https://github.com/pydata/xarray/pull/6795#issuecomment-1186349429,https://api.github.com/repos/pydata/xarray/issues/6795,1186349429,IC_kwDOAMm_X85GtkF1,4160723,2022-07-17T00:22:21Z,2022-07-17T00:24:01Z,MEMBER,"A few thoughts:

> how do we format indexes? Do we delegate to their __repr__ or some other method?

Like for variable data, Xarray indexes could implement `_repr_inline_` and `__repr__` to have both a summarized and detailed representation. They could also have a `_repr_html_` (for fancy representation of complex indexes).

> should we skip PandasIndex and PandasMultiIndex?

I'd skip it for the plain text DataArray / Dataset reprs (not a good information / verbosity ratio), but I'd keep it for the html repr (the index section could be collapsed by default) as well as for the `Indexes` repr.  We could also provide a display option for more control on this (e.g., a `display_default_indexes` option set to `False` by default).

> how do we present indexes that wrap multiple columns? At the moment, they are duplicated

Assuming that all coordinates related to a given index are shown next to each other, we could render the inline repr for the 1st coordinate and then use a short symbol (e.g., `--`, or a unicode symbol?) below that means ""it's the same index"".

> what do we do with the index marker in the coords repr?

I think we can keep it as-is. It helps to identify at a glance which coordinates are indexed and which aren't. And it's still relevant if we skip PandasIndex and PandasMultiIndex in the plain text DataArray / Dataset reprs.
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