Fix time indexer encoder and parser in fitting standardized index and…

[Hem-W]

Pull Request Checklist:

• This PR addresses an already opened issue (for bug fixes / features)
  • This PR fixes Fitted paramers reloaded from NC lead to errors in standardized index, and setting multiple indexers leads to inconsistent behaviour #1842
• Tests for the changes have been added (for bug fixes / features)
  • (If applicable) Documentation has been added / updated (for bug fixes / features)
• CHANGELOG.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?

Fix the encoder and parser for the time indexer in the xc.indices.stats.standardized_index_fit_params and xc.indices.stats.standardized_index to allow no indexer, non-array indexers, and multiple indexers.

Does this PR introduce a breaking change?

No. But the new parser is not compatible with the previous as the format of params.attrs["time_indexer"] is different. If any saved params from previous version were reloaded, it may lead to errors.

Other information:

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[aulemahal]

This looks excellent! Thanks a lot.

[aulemahal]

Now that I think of it, was there a need for using jsonpickle instead of the builtin json ?

jsonpickle is a dependency in xclim because of some stuff in sdba where json can't do the job. When the plan of taking sdba out of xclim is executed, we'll want to remove unneeded dependencies.

[Hem-W]

Now that I think of it, was there a need for using jsonpickle instead of the builtin json ?

jsonpickle is a dependency in xclim because of some stuff in sdba where json can't do the job. When the plan of taking sdba out of xclim is executed, we'll want to remove unneeded dependencies.

Thank you for pointing out. I believe json can meet the needs.

[github-actions]

Warning

This Pull Request is coming from a fork and must be manually tagged approved in order to perform additional testing.

[aulemahal]

Approved again, thanks!

[coveralls]

coverage: 90.679% (+0.02%) from 90.658%
when pulling 683e2a7 on Hem-W:fix-SI-time-indexer
into e01541e on Ouranosinc:main.