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feat: add Series|Expr cum_min and cum_max methods #1384

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merged 5 commits into from
Nov 16, 2024
Merged

feat: add Series|Expr cum_min and cum_max methods #1384

merged 5 commits into from
Nov 16, 2024

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FBruzzesi
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What type of PR is this? (check all applicable)

  • 💾 Refactor
  • ✨ Feature
  • 🐛 Bug Fix
  • 🔧 Optimization
  • 📝 Documentation
  • ✅ Test
  • 🐳 Other

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  • Code follows style guide (ruff)
  • Tests added
  • Documented the changes

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@github-actions github-actions bot added the enhancement New feature or request label Nov 15, 2024
FBruzzesi
FBruzzesi commented Nov 15, 2024
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narwhals/_arrow/series.py
Comment on lines +833 to +834
else pc.cumulative_min(native_series[::-1], skip_nulls=True)[::-1]
)
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Both this and pandas needs to reverse twice. Is there any other option?

@FBruzzesi
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Pyarrow introduced cumulative_min, cumulative_max and cumulative_prod in 13.0

@AlessandroMiola
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AlessandroMiola commented Nov 15, 2024 •
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Pyarrow introduced cumulative_min, cumulative_max and cumulative_prod in 13.0

Not sure if relevant, should we maybe also re-map these into their polars native exprs via POLARS_TO_ARROW_AGGREGATIONS for use in group_by like exprs? Found this might be relevant on #1177.

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FBruzzesi commented Nov 15, 2024 •
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Pyarrow introduced cumulative_min, cumulative_max and cumulative_prod in 13.0

Not sure if relevant, should we maybe also re-map these into their polars native exprs via POLARS_TO_ARROW_AGGREGATIONS for use in group_by like exprs? Found this might be relevant on #1177.

That's a very good point. However for arrow this is not possible, unless we move operations unsupported natively to use __iter__, but that would most likely be slow (List of pyarrow grouped aggregations).

Regarding pandas, I will check that's possible to achieve and add tests. However I am a bit hesitant due to the impossibility of passing arguments along (reverse=True)

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That's a very good point. However for arrow this is not possible, unless we move operations unsupported natively to use __iter__, but that would most likely be slow (List of pyarrow grouped aggregations).

ahhh, right, I see ✌️

@FBruzzesi FBruzzesi changed the title feat: add Series|Expr.cum_min method feat: add Series|Expr cum_min and cum_max methods Nov 16, 2024
@FBruzzesi FBruzzesi mentioned this pull request Nov 16, 2024
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MarcoGorelli
MarcoGorelli approved these changes Nov 16, 2024
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awesome, thanks @FBruzzesi !

@MarcoGorelli MarcoGorelli merged commit 8ed6e7e into main Nov 16, 2024
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@FBruzzesi FBruzzesi deleted the feat/cum-min branch November 16, 2024 10:09
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@MarcoGorelli MarcoGorelli MarcoGorelli approved these changes

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@FBruzzesi @AlessandroMiola @MarcoGorelli