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/1614#issuecomment-398172901,https://api.github.com/repos/pydata/xarray/issues/1614,398172901,MDEyOklzc3VlQ29tbWVudDM5ODE3MjkwMQ==,5635139,2018-06-18T19:46:39Z,2020-03-26T20:39:49Z,MEMBER,"> consider some kind of history tracker as part of the metadata propagation? 

Data lineage is a big, hard, unsolved problem (~for us~ internally, above both naming things and cache invalidation :) )

To second @shoyer, I think it's big and difficult enough to be a separate library","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,264049503
https://github.com/pydata/xarray/issues/1614#issuecomment-435621629,https://api.github.com/repos/pydata/xarray/issues/1614,435621629,MDEyOklzc3VlQ29tbWVudDQzNTYyMTYyOQ==,1217238,2018-11-03T21:18:11Z,2018-11-03T21:18:11Z,MEMBER,"> I would happy to add a global keep_attrs option to xarray.set_options(), which we could use for controlling arithmetic. I'm not planning on working on it personally, but I would be happy to review a PR.

Note that this was implemented by @TomNicholas in https://github.com/pydata/xarray/pull/2482","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,264049503
https://github.com/pydata/xarray/issues/1614#issuecomment-434787209,https://api.github.com/repos/pydata/xarray/issues/1614,434787209,MDEyOklzc3VlQ29tbWVudDQzNDc4NzIwOQ==,500246,2018-10-31T17:56:41Z,2018-10-31T17:56:41Z,CONTRIBUTOR,Another one to decide is `xarray.zeros_like(...)` and friends.,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,264049503
https://github.com/pydata/xarray/issues/1614#issuecomment-398204944,https://api.github.com/repos/pydata/xarray/issues/1614,398204944,MDEyOklzc3VlQ29tbWVudDM5ODIwNDk0NA==,1217238,2018-06-18T21:41:46Z,2018-06-18T21:41:46Z,MEMBER,"I would happy to add a global `keep_attrs` option to `xarray.set_options()`, which we could use for controlling arithmetic. I'm not planning on working on it personally, but I would be happy to review a PR.","{""total_count"": 4, ""+1"": 4, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,264049503
https://github.com/pydata/xarray/issues/1614#issuecomment-398203726,https://api.github.com/repos/pydata/xarray/issues/1614,398203726,MDEyOklzc3VlQ29tbWVudDM5ODIwMzcyNg==,8204522,2018-06-18T21:36:32Z,2018-06-18T21:36:32Z,NONE,"@shoyer, I assume you are referring to the `keep_attrs` option. Is there a way to persist `attrs` during arithmetic options? I find myself writing a bunch of boilerplate to transfer the wealth of metadata included with most netCDF files.

I realize that adding a module-level or `DataArray` instance-specific `maintain_attrs` configuration flag (as discussed in #131, #988, #1271) could be problematic, but this strikes me as complexity worth adding. The current approach of dropping all metadata (not just units) seems heavy-handed and unintuitive for new/casual users. As you mentioned in #1271, better to have stale metadata than no metadata at all.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,264049503
https://github.com/pydata/xarray/issues/1614#issuecomment-398197376,https://api.github.com/repos/pydata/xarray/issues/1614,398197376,MDEyOklzc3VlQ29tbWVudDM5ODE5NzM3Ng==,1217238,2018-06-18T21:12:18Z,2018-06-18T21:12:18Z,MEMBER,"> No, just the proposed feature to keep or delete metadata based on the various operations. Is this behaviour already part of the library, and this issue is just to clarify the intended behaviour, or is this a feature proposal?

We already have most of this behavior (matching what @jhamman lists in the first comment), though it isn't clearly documented. It should just work if you use xarray methods/functions.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,264049503
https://github.com/pydata/xarray/issues/1614#issuecomment-398183428,https://api.github.com/repos/pydata/xarray/issues/1614,398183428,MDEyOklzc3VlQ29tbWVudDM5ODE4MzQyOA==,5225190,2018-06-18T20:23:41Z,2018-06-18T20:23:52Z,NONE,"> are you referring to a different issue? the first post only summarizes some simple proposed rules.

No, just the proposed feature to keep or delete metadata based on the various operations. Is this behaviour already part of the library, and this issue is just to clarify the intended behaviour, or is this a feature proposal?","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,264049503
https://github.com/pydata/xarray/issues/1614#issuecomment-398153267,https://api.github.com/repos/pydata/xarray/issues/1614,398153267,MDEyOklzc3VlQ29tbWVudDM5ODE1MzI2Nw==,1217238,2018-06-18T18:36:50Z,2018-06-18T18:36:50Z,MEMBER,"> Also - might I suggest you consider some kind of history tracker as part of the metadata propagation? 

Certainly this would be out of scope for xarray itself, but this perhaps be done with a library that wraps xarray's API. If I recall correctly, @pwolfram was also interested in this.

We did discuss customizable hooks for attribute handling in #988 but I'm no longer sure that is a good idea. These sort of overloads are really hard to get right, as we've seen with NumPy's long history of different override protocols (the most recent example being `__array_ufunc__`).","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,264049503
https://github.com/pydata/xarray/issues/1614#issuecomment-398151360,https://api.github.com/repos/pydata/xarray/issues/1614,398151360,MDEyOklzc3VlQ29tbWVudDM5ODE1MTM2MA==,1217238,2018-06-18T18:30:16Z,2018-06-18T18:30:16Z,MEMBER,"> Hi, this feature would be very relevant to the intended use case of a project I'd like to use xarray for. Is the behaviour discussed in the first post implemented anywhere, e.g. in the trunk, for me to play with?

are you referring to a different issue? the first post only summarizes some simple proposed rules.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,264049503
https://github.com/pydata/xarray/issues/1614#issuecomment-397966050,https://api.github.com/repos/pydata/xarray/issues/1614,397966050,MDEyOklzc3VlQ29tbWVudDM5Nzk2NjA1MA==,5225190,2018-06-18T07:32:08Z,2018-06-18T07:32:08Z,NONE,"Also - might I suggest you consider some kind of history tracker as part of the metadata propagation? Perhaps metadata could be saved from each step of a set of operations, so that there is a full paper trail for the set of operations have been applied to the data. It could however get complicated to merge together objects with their own separate histories, especially if they ultimately descend from the same original data set.

This would be very relevant for scientific analyses.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,264049503
https://github.com/pydata/xarray/issues/1614#issuecomment-397965247,https://api.github.com/repos/pydata/xarray/issues/1614,397965247,MDEyOklzc3VlQ29tbWVudDM5Nzk2NTI0Nw==,5225190,2018-06-18T07:28:32Z,2018-06-18T07:28:32Z,NONE,"Hi, this feature would be very relevant to the intended use case of a project I'd like to use `xarray` for. Is the behaviour discussed in the first post implemented anywhere, e.g. in the trunk, for me to play with?","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,264049503
https://github.com/pydata/xarray/issues/1614#issuecomment-362752398,https://api.github.com/repos/pydata/xarray/issues/1614,362752398,MDEyOklzc3VlQ29tbWVudDM2Mjc1MjM5OA==,1217238,2018-02-03T00:38:12Z,2018-02-03T00:38:12Z,MEMBER,"The challenge with a user-specified function is that there can potentially be weird conflicts if multiple libraries try to override it. Possibly it's worth it for the convenience, but subclasses allowing for explicit hooks (like numpy) is probably the cleanest solution.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,264049503
https://github.com/pydata/xarray/issues/1614#issuecomment-362624658,https://api.github.com/repos/pydata/xarray/issues/1614,362624658,MDEyOklzc3VlQ29tbWVudDM2MjYyNDY1OA==,5442433,2018-02-02T15:54:41Z,2018-02-02T15:54:41Z,NONE,"I am also interested. In terms of the table from @jhamman I am in principle ok with. However, there could be an option to refer to the original attrs in order to provide provenance even on operations like reduce and arithmetic. The idea here is reproducibility and tractability. Maybe an 'origin' attribute?","{""total_count"": 3, ""+1"": 3, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,264049503
https://github.com/pydata/xarray/issues/1614#issuecomment-362529551,https://api.github.com/repos/pydata/xarray/issues/1614,362529551,MDEyOklzc3VlQ29tbWVudDM2MjUyOTU1MQ==,167802,2018-02-02T09:13:38Z,2018-02-02T09:13:38Z,CONTRIBUTOR,This issue is very relevant for me too. I would like to also propose that a user could provide a function that would know how to combine the `attrs` of different DataArrays.,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,264049503
https://github.com/pydata/xarray/issues/1614#issuecomment-343617001,https://api.github.com/repos/pydata/xarray/issues/1614,343617001,MDEyOklzc3VlQ29tbWVudDM0MzYxNzAwMQ==,8204522,2017-11-10T23:50:18Z,2017-11-10T23:50:18Z,NONE,"I'd also suggest that a global [option](http://xarray.pydata.org/en/stable/generated/xarray.set_options.html) of always_keep_attrs=True would be useful. While I understand the logic of dropping units during certain operations, it makes attributes unusable for storing other miscellaneous metadata, e.g. on data provenance. As a recent xarray convert, this behavior has been frustrating.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,264049503