polars.DataFrame.sort

DataFrame.sort(

by: IntoExpr | Iterable[IntoExpr],

*more_by: IntoExpr,

descending: bool | Sequence[bool] = False,

nulls_last: bool | Sequence[bool] = False,

multithreaded: bool = True,

maintain_order: bool = False,

) → DataFrame

Sort the dataframe by the given columns.

Parameters:

by

Column(s) to sort by. Accepts expression input. Strings are parsed as column names.

*more_by

Additional columns to sort by, specified as positional arguments.

descending

Sort in descending order. When sorting by multiple columns, can be specified per column by passing a sequence of booleans.

nulls_last

Place null values last; can specify a single boolean applying to all columns or a sequence of booleans for per-column control.

multithreaded

Sort using multiple threads.

maintain_order

Whether the order should be maintained if elements are equal.

Examples

Pass a single column name to sort by that column.

>>> df = pl.DataFrame(
...     {
...         "a": [1, 2, None],
...         "b": [6.0, 5.0, 4.0],
...         "c": ["a", "c", "b"],
...     }
... )
>>> df.sort("a")
shape: (3, 3)
┌──────┬─────┬─────┐
│ a    ┆ b   ┆ c   │
│ ---  ┆ --- ┆ --- │
│ i64  ┆ f64 ┆ str │
╞══════╪═════╪═════╡
│ null ┆ 4.0 ┆ b   │
│ 1    ┆ 6.0 ┆ a   │
│ 2    ┆ 5.0 ┆ c   │
└──────┴─────┴─────┘

Sorting by expressions is also supported.

>>> df.sort(pl.col("a") + pl.col("b") * 2, nulls_last=True)
shape: (3, 3)
┌──────┬─────┬─────┐
│ a    ┆ b   ┆ c   │
│ ---  ┆ --- ┆ --- │
│ i64  ┆ f64 ┆ str │
╞══════╪═════╪═════╡
│ 2    ┆ 5.0 ┆ c   │
│ 1    ┆ 6.0 ┆ a   │
│ null ┆ 4.0 ┆ b   │
└──────┴─────┴─────┘

Sort by multiple columns by passing a list of columns.

>>> df.sort(["c", "a"], descending=True)
shape: (3, 3)
┌──────┬─────┬─────┐
│ a    ┆ b   ┆ c   │
│ ---  ┆ --- ┆ --- │
│ i64  ┆ f64 ┆ str │
╞══════╪═════╪═════╡
│ 2    ┆ 5.0 ┆ c   │
│ null ┆ 4.0 ┆ b   │
│ 1    ┆ 6.0 ┆ a   │
└──────┴─────┴─────┘

Or use positional arguments to sort by multiple columns in the same way.

>>> df.sort("c", "a", descending=[False, True])
shape: (3, 3)
┌──────┬─────┬─────┐
│ a    ┆ b   ┆ c   │
│ ---  ┆ --- ┆ --- │
│ i64  ┆ f64 ┆ str │
╞══════╪═════╪═════╡
│ 1    ┆ 6.0 ┆ a   │
│ null ┆ 4.0 ┆ b   │
│ 2    ┆ 5.0 ┆ c   │
└──────┴─────┴─────┘