jiayuasu opened a new pull request, #859:
URL: https://github.com/apache/sedona-db/pull/859
Continues the Phase P2 work of #791 with pandas-style `sort_values` on the
lazy `DataFrame`.
## API
```python
df.sort_values(by="x")
df.sort_values(by="x", ascending=False)
df.sort_values(by=["x", "y"])
df.sort_values(by=["x", "y"], ascending=[True, False]) # mixed
df.sort_values(by=col("x") + col("y")) # Expr key
df.sort_values(by=[col("x"), "y"]) # mixed str / Expr
```
`by` accepts `str | Expr | list[str | Expr]`. `ascending` is `bool |
list[bool]` (broadcast to `by` length if scalar, must match if list).
## Two semantic calls worth flagging
**Nulls last in both directions.** Pandas's default is `na_position='last'`
regardless of direction; DataFusion's SQL-style default is nulls-first on
descending. We override DataFusion's default so pandas users porting code get
the placement they expect. If the SQL behavior is needed, `sd.sql("... ORDER BY
... NULLS FIRST")` is still the escape hatch.
**No `inplace=` kwarg.** Our `DataFrame` wraps an immutable DataFusion
`LogicalPlan`, so true in-place mutation is impossible. Rather than silently
warn-and-ignore (the design-doc default, which leaves callers with an unsorted
frame they ignored the return value of), the kwarg is simply not defined —
Python raises the standard `TypeError: sort_values() got an unexpected keyword
argument 'inplace'`. A test locks that contract. The design doc will be updated
to match in a follow-up.
## Test plan
17 tests in `tests/expr/test_dataframe_sort_values.py`:
- **Positive**: single key asc/desc, by `col(...)` Expr, by computed Expr
(`col("x") + col("y")`), multi-key all-asc, multi-key mixed asc/desc with
deliberately scrambled input so a broken implementation cannot pass,
ascending-scalar-broadcast, nulls-last asc, nulls-last desc.
- **Lazy return**: `isinstance(out, DataFrame)` (not `hasattr`, per Dewey's
policy).
- **Errors**: empty `by`, length mismatch, bad `by` type, bad `by` element
type (matched on a phrase only that error path uses), bad `ascending` type, bad
`ascending` list element, `inplace=` rejected by Python.
All assertions use `pd.testing.assert_frame_equal` for outputs and
`pytest.raises(..., match="discriminating phrase")` for errors. No
substring-on-a-single-character patterns.
Local: 17 unit + 18 doctests + `ruff format` + `ruff check` all green.
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