issues: 1364388790

This data as json

id node_id number title user state locked assignee milestone comments created_at updated_at closed_at author_association active_lock_reason draft pull_request body reactions performed_via_github_app state_reason repo type
1364388790 I_kwDOAMm_X85RUuu2 7002 Custom indexes and coordinate (re)ordering 4160723 open 0     2 2022-09-07T09:44:12Z 2023-08-23T14:35:32Z   MEMBER      

What is your issue?

(From https://github.com/pydata/xarray/issues/5647#issuecomment-946546464).

The current alignment logic (as refactored in #5692) requires that two compatible indexes (i.e., of the same type) must relate to one or more coordinates with matching names but also in a matching order.

For some multi-coordinate indexes like PandasMultiIndex this makes sense. However, for other multi-coordinate indexes (e.g., staggered grid indexes) the order of the coordinates doesn't matter much.

Possible options:

  1. Setting new Xarray indexes may reorder the coordinate variables, possibly via Index.create_variables(), to ensure consistent order
  2. Xarray indexes must implement a Index.matching_key abstract property in order to support re-indexing and alignment.
  3. Take care of coordinate order (and maybe other things) inside Index.join and Index.equals, e.g., for PandasMultiIndex maybe reorder the levels beforehand.
    • pros: more flexible
    • cons: not great to implicitly reorder levels if it's a costly operation?
  4. Find matching indexes using a two-passes approach: (1) group all indexes by dimension name and (2) check compatibility between the indexes listed in each group.
 
{
    "url": "https://api.github.com/repos/pydata/xarray/issues/7002/reactions",
    "total_count": 0,
    "+1": 0,
    "-1": 0,
    "laugh": 0,
    "hooray": 0,
    "confused": 0,
    "heart": 0,
    "rocket": 0,
    "eyes": 0
}
     13221727 issue

Links from other tables