[Refactor]: Validate fix in PR #750 for #759

[tomvothecoder]

Description

• Closes #759

5/30/24

• [x] Re-run ex1.py and perform regression test again
• [x] Check for diffs
  • NET_FLUX_SRF and RESTOM had the largest diffs with the slice flag -- now fixed
• [x] Debug diffs
  • [x] Fix "TREFHT" land large diff with mean metrics -- due to incorrect Xarray datasets being passed to _subset_on_region() (need to pass objects with land mask applied)
  • [x] Fix TREFHT land mean ref regridded data (11.59% diff) -- address this later in a separate GH issue (#817)

Checklist

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] My changes generate no new warnings
• [x] Any dependent changes have been merged and published in downstream modules

If applicable:

• [ ] New and existing unit tests pass with my changes (locally and CI/CD build)
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] I have noted that this is a breaking change for a major release (fix or feature that would cause existing functionality to not work as expected)

[tomvothecoder]

Hey @chengzhuzhang, just an FYI that I added functionality to replicate the cdms2 "ccb flag for non-submonthly data (#759).

I tested ex1.py which uses time series data and all of the results check out except one (new issue #817). You can refer to the above review comment for more info.

You can review the new code for this functionality here in dataset_xr.py: https://github.com/E3SM-Project/e3sm_diags/pull/750/files#diff-35006a05805f6f5876c9fe70b5281c865955b8a82d1574fd7f62d6efda623975

[chengzhuzhang]

@tomvothecoder great work to support the slice flag and match the results with main! Also thanks for careful documentation on the final straggler and I agree that we should address in a separate PR..