Add NestedFrame.reduce

[wilsonbb]

Change Description

To address #14, here we provide an easy way for users to apply a custom function to a NestedFrame, where the user-provided function is applied to each row of the base layer of the NestedFrame along the specified columns (including the ability to specify nested columns packed into that row). The result of the function is then another nested frame which can be worked with separately or joined back to the original frame.

We opted for the provisional name reduce since it provides to the user function "base" layer columns as scalars and hierarchical columns as collections allowing for the "reduction" of the hierarchical data to a frame matching the indices of the base layer. For other cases of providing a custom function, the user can still. the use the apply API.

• My PR includes a link to the issue that I am addressing

Solution Description

This solution wraps around pandas.DataFrame.apply to apply the user function to each row of the nested frame. Note that for columns in the "nested" frames, these are already packed as a dataframe within their respective cells of that row. So we do not need to unpack and flatten in the case where a user requests hierarchical columns.

Code Quality

• I have read the Contribution Guide
• My code follows the code style of this project
• My code builds (or compiles) cleanly without any errors or warnings
• My code contains relevant comments and necessary documentation

New Feature Checklist

• I have added or updated the docstrings associated with my feature using the NumPy docstring format
• I have updated the tutorial to highlight my new feature (if appropriate)
• I have added unit/End-to-End (E2E) test cases to cover my new feature
• My change includes a breaking change
  • My change includes backwards compatibility and deprecation warnings (if possible)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.63%. Comparing base (ac4032f) to head (71594b5).

❗ Current head 71594b5 differs from pull request most recent head bbd14fd. Consider uploading reports for the commit bbd14fd to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #32      +/-   ##
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+ Coverage   95.47%   95.63%   +0.15%     
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  Files          14       14              
  Lines         597      618      +21     
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+ Hits          570      591      +21     
  Misses         27       27              

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[github-actions]

Before [ac4032f]	After [812bc2b]	Ratio	Benchmark (Parameter)
360	2.28k	6.33	benchmarks.mem_list
2.95±0.9s	2.84±1s	0.96	benchmarks.time_computation

Click here to view all benchmarks.

[dougbrn]

Looks good! I don't have any technical blockers, just a couple of un-actionable thoughts.