issue_comments

@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.

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?

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.

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?

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?

I'd also suggest that a global option 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.