Bug fix when using HamiltonTracker with polars dataframes

[elyase]

Fixes an error when tracking in the hamilton ui with polars dataframes:

    return col.str.lengths()
           ^^^^^^^^^^^^^^^
AttributeError: 'StringNameSpace' object has no attribute 'lengths'

Changes

Use the correct polars method

How I tested this

Run the code and it doesn't error anymore

Notes

Checklist

• PR has an informative and human-readable title (this will be pulled into the release notes)
• Changes are limited to a single goal (no scope creep)
• Code passed the pre-commit check & code is left cleaner/nicer than when first encountered.
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged / future TODOs are captured in comments
• Project documentation has been updated if adding/changing functionality.

[elijahbenizzy]

Hey! Thanks for this -- seems reasonable on first glance.

Two thoughts:

1. Is this due a polars version? Might be that it used to work.
2. Looks like this was not added in the tests, so my guess on (1) is it never worked: https://github.com/DAGWorks-Inc/hamilton/blob/004ac5e4efd8aefa45a1888b3c2df375f2843370/ui/sdk/tests/tracking/test_polars_col_stats.py Would be nice to have tests (if you want to add, should be easy to copy/paste/adjust those), but I don't want this to be a blocker to you getting your fix in.

So if you're up to the challenge of adding tests feel free to, otherwise we can add some a bit later.

[elyase]

@elijahbenizzy yes the names changed after polars==0.18. I added a test for the fix

[elijahbenizzy]

@elijahbenizzy yes the names changed after polars==0.18. I added a test for the fix

Great -- this looks good. Mind running pre-commit changes? pre-commit run --all should do it. Then we'll merge! Appreciate the fix/test 🙌

[elyase]

✔️ thanks to you all for hamilton!

[elijahbenizzy]

Thank you for your contribution! Can do a quick patch release for the SDK shortly.