Deprecate calendar ops

[aulemahal]

Pull Request Checklist:

• This PR addresses an already opened issue (for bug fixes / features)
  • This PR fixes most of the Phase out convert_calendar and some units processing #1010 issue.
• Tests for the changes have been added (for bug fixes / features) (mostly removed)
  • (If applicable) Documentation has been added / updated (for bug fixes / features)
• CHANGES.rst has been updated (with summary of main changes)
  • Link to issue (:issue:number) and pull request (:pull:number) has been added

What kind of change does this PR introduce?

• Calendar utilities that have an equivalent in xarray have been deprecated and will be removed in 0.51. This concerns the following members of xclim.core.calendar:
  • convert_calendar : Use Dataset.convert_calendar, DataArray.convert_calendar or xr.coding.calendar_ops.convert_calendar instead.
    • If your code passes target as an array, first convert the source to the target's calendar and then reindex the result to target.
    • If you were using the doy=True option, replace it with xc.core.calendar.convert_doy(source, target_cal).convert_calendar(target_cal).
    • "default" is no longer a valid calendar name for any xclim functions and will not be returned by get_calendar. Xarray has a use_cftime argument, xclim exposes it when the distinction is needed.
  • date_range : Use xarray.date_range instead.
  • date_range_like: Use xarray.date_range_like instead.
  • interp_calendar : Use xarray.coding.calendar_ops.interp_calendar instead.
  • days_in_year : Use xarray.coding.calendar_ops._days_in_year instead.
  • datetime_to_decimal_year : Use xarray.coding.calendar_ops._datetime_to_decimal_year instead.

Does this PR introduce a breaking change?

Yes.

• Some options of convert_calendar are not possible with xarray, suggestions are made above.
• "default" is not a calendar name anymore.

Other information:

[review-notebook-app]

Check out this pull request on 

See visual diffs & provide feedback on Jupyter Notebooks.

---

Powered by ReviewNB

[Zeitsperre]

Looks good!