narwhals-dev

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• Dask: wrong results in unique, str.split, over, n_unique, var and mean_horizontal

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  dask

  Difficulty 4/5 3-5 days Newbie friendliness 48/100

  narwhals-dev/narwhals#4153 · Opened Nov 13, 2026

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• [Enh]: Allow scalar Boolean filters

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  Difficulty 3/5 1-2 days Newbie friendliness 58/100

  narwhals-dev/narwhals#4118 · 4 comments · Opened Oct 29, 2026

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• Duplicate column names are handled inconsistently across backends (DuckDB and Ibis fail silently)

  May be free again @swethakommuri claimed this 22 days ago, and no pull request is open. Open

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  bug: incorrect result

  Difficulty 4/5 3-5 days Newbie friendliness 43/100

  narwhals-dev/narwhals#4103 · 3 comments · Opened Oct 22, 2026

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• [Enh]: Polars 2.0 support

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  Difficulty 5/5 Over a week Newbie friendliness 35/100

  narwhals-dev/narwhals#4101 · 2 comments · Opened Oct 22, 2026

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• [Bug]: `-2**63 // -1` inconsistent across backends, SQLFrame silently returns a float

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  Difficulty 5/5 Over a week Newbie friendliness 15/100

  narwhals-dev/narwhals#4071 · 4 comments · Opened Oct 13, 2026

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• [Enh](discussion): float `// 0.0` returns null on every backend except Polars, which one is intended?

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  Difficulty 5/5 Over a week Newbie friendliness 15/100

  narwhals-dev/narwhals#4070 · Opened Oct 13, 2026

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• `TypeIs` guard does not narrow mixed input union in Pyrefly

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  Difficulty 4/5 1-2 days Newbie friendliness 42/100

  narwhals-dev/narwhals#4064 · 1 comment · Opened Oct 12, 2026

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• `maintain_order` for `DataFrame.join`

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  enhancement

  Difficulty 3/5 Half a day Newbie friendliness 25/100

  narwhals-dev/narwhals#4048 · 5 comments · Opened Oct 9, 2026

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• [Bug]: cum_max is wrong for non-positive floats on the PyArrow backend (upstream apache/arrow#51194, fixed but unreleased)

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  Difficulty 3/5 1-2 days Newbie friendliness 42/100

  narwhals-dev/narwhals#4033 · Opened Oct 5, 2026

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• Decide which `backend=` spellings resolve to a plugin

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  extensibility needs discussion

  Difficulty 5/5 Over a week Newbie friendliness 25/100

  narwhals-dev/narwhals#4026 · 4 comments · Opened Oct 4, 2026

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• Generalize `_hasattr_static` into a static "is this really implemented?" check

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  enhancement internal needs discussion

  Difficulty 4/5 3-5 days Newbie friendliness 48/100

  narwhals-dev/narwhals#4025 · Opened Oct 4, 2026

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• [Bug]: integer `sum()` returns `Decimal(38, 0)` on the DuckDB backend, and arithmetic on the result raises

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  Difficulty 4/5 3-5 days Newbie friendliness 52/100

  narwhals-dev/narwhals#4014 · 3 comments · Opened Oct 2, 2026

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• pandas: .cast() inside group_by().agg() is dropped when the aggregation takes the complex group-by path

  May be free again A pull request for this issue was closed without being merged. Open

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  Difficulty 3/5 1-2 days Newbie friendliness 30/100

  narwhals-dev/narwhals#4005 · Opened Sep 29, 2026

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• [Bug]: `Expr.clip` with a scalar-like receiver behaves differently on every backend

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  api design bug: incorrect result needs discussion

  Difficulty 4/5 3-5 days Newbie friendliness 48/100

  narwhals-dev/narwhals#3964 · Opened Sep 19, 2026

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• [Enh]: Document and test chDB interoperability through Arrow

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  Difficulty 3/5 1-2 days Newbie friendliness 65/100

  narwhals-dev/narwhals#3932 · Opened Sep 9, 2026

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• Decide on a cross-backend coercion for `is_in` & `__contains__`

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  needs discussion

  Difficulty 5/5 Over a week Newbie friendliness 25/100

  narwhals-dev/narwhals#3900 · 2 comments · Opened Sep 4, 2026

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• DuckDB Python Relational API Tracker

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  duckdb upstream issue

  Difficulty 4/5 3-5 days Newbie friendliness 45/100

  narwhals-dev/narwhals#3883 · Opened Aug 26, 2026

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• Benchmark follow-ups

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  performance

  Difficulty 3/5 1-2 days Newbie friendliness 48/100

  narwhals-dev/narwhals#3877 · Opened Aug 25, 2026

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• Use pure-Python build system instead of uv or provide a fallback

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  build needs discussion

  Difficulty 4/5 3-5 days Newbie friendliness 38/100

  narwhals-dev/narwhals#3811 · 11 comments · Opened Jul 21, 2026

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• [Bug]: constructing a Categorical column from Python values raises on the PyArrow backend

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  bug: it raises an error but shouldn't categorical pyarrow upstream issue

  Difficulty 3/5 1-2 days Newbie friendliness 55/100

  narwhals-dev/narwhals#3775 · 5 comments · Opened Jul 10, 2026

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• Simplify `DataFrame.from_numpy` with `schema: Sequence[str]`

  May be free again @dangotbanned claimed this 126 days ago, and no pull request is open. Open

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  internal low priority

  narwhals-dev/narwhals#3774 · 1 reaction · 1 assignee · Opened Jul 10, 2026

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• enh: add `nw.Categories`

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  categorical dtypes enhancement

  Difficulty 4/5 3-5 days Newbie friendliness 32/100

  narwhals-dev/narwhals#3736 · Opened Jul 1, 2026

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• Re-enable coverage for `ibis`

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  ci ibis

  Difficulty 2/5 1-3 hours Newbie friendliness 62/100

  narwhals-dev/narwhals#3726 · 6 comments · Opened Jun 29, 2026

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• Dependency Dashboard

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  dependencies

  Difficulty 4/5 3-5 days Newbie friendliness 20/100

  narwhals-dev/narwhals#3705 · Opened Jun 22, 2026

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• [Enh]: Add strict option to cast

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  dtypes enhancement

  Difficulty 4/5 3-5 days Newbie friendliness 54/100

  narwhals-dev/narwhals#3702 · 3 comments · 2 reactions · Opened Jun 21, 2026

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• bug: pylance blows up on polars

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  needs investigation polars typing

  Difficulty 4/5 3-5 days Newbie friendliness 38/100

  narwhals-dev/narwhals#3643 · 2 comments · Opened May 19, 2026

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• Tracking: `uv` migration

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  internal

  Difficulty 5/5 Over a week Newbie friendliness 25/100

  narwhals-dev/narwhals#3635 · Opened May 16, 2026

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• Utilizing `uv` workspaces

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  dependencies developer tools internal

  Difficulty 5/5 Over a week Newbie friendliness 25/100

  narwhals-dev/narwhals#3634 · 1 comment · Opened May 16, 2026

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• Add an AI Policy

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  developer tools documentation

  Difficulty 3/5 1-2 days Newbie friendliness 48/100

  narwhals-dev/narwhals#3632 · 5 comments · 1 reaction · Opened May 16, 2026

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• ci: Improving `generate_random_versions`

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  ci needs discussion tests

  Difficulty 4/5 3-5 days Newbie friendliness 30/100

  narwhals-dev/narwhals#3623 · 5 comments · Opened May 14, 2026

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• ci: run `ty` and `zuban` on test suite

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  typing

  Difficulty 3/5 1-2 days Newbie friendliness 53/100

  narwhals-dev/narwhals#3606 · 2 comments · Opened May 8, 2026

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• typing: Narrow `.lazy(...)` return type when possible

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  typing

  Difficulty 5/5 Over a week Newbie friendliness 25/100

  narwhals-dev/narwhals#3590 · 12 comments · Opened May 3, 2026

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• bug: fetch_rel_time_zone fails with read-only MotherDuck connection

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  Difficulty 4/5 3-5 days Newbie friendliness 48/100

  narwhals-dev/narwhals#3567 · 14 comments · Opened Apr 24, 2026

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• docs: Possible improvements

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  documentation

  Difficulty 3/5 1-2 days Newbie friendliness 38/100

  narwhals-dev/narwhals#3543 · 1 reaction · Opened Apr 11, 2026

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• [Enh]: support `Expr.map_elements`

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  Difficulty 5/5 Over a week Newbie friendliness 30/100

  narwhals-dev/narwhals#3512 · 5 comments · Opened Mar 15, 2026

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• [Enh]: Add `Expr.str.json_decode`

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  enhancement

  Difficulty 4/5 3-5 days Newbie friendliness 38/100

  narwhals-dev/narwhals#3506 · 11 comments · Opened Mar 5, 2026

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• [Enh]: nw.scan_ndjson as a function, passing narwhals schema

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  Difficulty 5/5 Over a week Newbie friendliness 30/100

  narwhals-dev/narwhals#3505 · Opened Mar 5, 2026

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• Properly documenting `ExprIR`

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  documentation internal

  Difficulty 4/5 3-5 days Newbie friendliness 28/100

  narwhals-dev/narwhals#3497 · 1 comment · 4 reactions · Opened Mar 3, 2026

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• [Doc]: Linting the example from the README gives an error when using `ty`.

  May be free again A pull request for this issue was closed without being merged. Open

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  documentation typing

  Difficulty 4/5 3-5 days Newbie friendliness 25/100

  narwhals-dev/narwhals#3493 · 9 comments · Opened Mar 2, 2026

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• [Bug]: Typing--cannot chain function taking FrameT with nw.from_native()

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  Difficulty 4/5 3-5 days Newbie friendliness 30/100

  narwhals-dev/narwhals#3486 · Opened Feb 25, 2026

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• [Enh]: Add support for pyspark interval data types

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  dtypes enhancement spark-like

  Difficulty 4/5 3-5 days Newbie friendliness 42/100

  narwhals-dev/narwhals#3431 · 2 comments · Opened Jan 31, 2026

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• Tracking: Adopt `ty` as an (additional) type checker

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  typing upstream issue

  Difficulty 5/5 Over a week Newbie friendliness 25/100

  narwhals-dev/narwhals#3409 · 1 comment · 7 reactions · Opened Jan 21, 2026

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• silence or override pandas warning about downcasting?

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  Difficulty 3/5 1-2 days Newbie friendliness 35/100

  narwhals-dev/narwhals#3394 · 1 comment · Opened Jan 9, 2026

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• [Enh]: Add support for `concat(..., how={"vertical_relaxed", "diagonal_relaxed"})`

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  dtypes enhancement

  Difficulty 5/5 Over a week Newbie friendliness 30/100

  narwhals-dev/narwhals#3386 · 1 comment · 2 reactions · Opened Jan 3, 2026

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• use protocols instead of optional 3rd party dependencies in public type annotations

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  typing

  Difficulty 4/5 3-5 days Newbie friendliness 35/100

  narwhals-dev/narwhals#3374 · 4 comments · 1 reaction · Opened Dec 29, 2025

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• Add `{*Frame,Series,Expr}.drop_nans`

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  enhancement

  Difficulty 4/5 3-5 days Newbie friendliness 35/100

  narwhals-dev/narwhals#3366 · 5 comments · Opened Dec 22, 2025

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• enh: add (optional) `order_by` to `rolling_*`, `cum_*`, `first`, ...

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  enhancement

  Difficulty 4/5 3-5 days Newbie friendliness 28/100

  narwhals-dev/narwhals#3363 · 2 comments · Opened Dec 19, 2025

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• [Enh]: add LazyFrame.collect_batches

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  enhancement

  Difficulty 4/5 3-5 days Newbie friendliness 35/100

  narwhals-dev/narwhals#3360 · 15 comments · Opened Dec 18, 2025

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• [Enh]: Chain operations before .over() for LazyFrames

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  enhancement harder than it looks

  Difficulty 4/5 3-5 days Newbie friendliness 38/100

  narwhals-dev/narwhals#3358 · 1 comment · 1 reaction · Opened Dec 17, 2025

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• [Enh]: add support for Expr.list.eval

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  enhancement

  Difficulty 4/5 3-5 days Newbie friendliness 35/100

  narwhals-dev/narwhals#3351 · 1 comment · 1 reaction · Opened Dec 13, 2025

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