polars.LazyFrame.rename

LazyFrame.rename(
    mapping: Mapping[str,
    str] | Callable[[str],
    str],
    *,
    strict: bool = True,
) → LazyFrame

Rename column names.

engine:In MemoryStreamingDistributed

Parameters:

mapping

Key value pairs that map from old name to new name, or a function that takes the old name as input and returns the new name.

strict

Validate that all column names exist in the current schema, and throw an exception if any do not. (Note that this parameter is a no-op when passing a function to mapping).

See also

Expr.name.replace

Notes

If existing names are swapped (e.g. ‘A’ points to ‘B’ and ‘B’ points to ‘A’), polars will block projection and predicate pushdowns at this node.

Examples

>>> lf = pl.LazyFrame(
...     {
...         "foo": [1, 2, 3],
...         "bar": [6, 7, 8],
...         "ham": ["a", "b", "c"],
...     }
... )
>>> lf.rename({"foo": "apple"}).collect()
shape: (3, 3)
┌───────┬─────┬─────┐
│ apple ┆ bar ┆ ham │
│ ---   ┆ --- ┆ --- │
│ i64   ┆ i64 ┆ str │
╞═══════╪═════╪═════╡
│ 1     ┆ 6   ┆ a   │
│ 2     ┆ 7   ┆ b   │
│ 3     ┆ 8   ┆ c   │
└───────┴─────┴─────┘
>>> lf.rename(lambda column_name: "c" + column_name[1:]).collect()
shape: (3, 3)
┌─────┬─────┬─────┐
│ coo ┆ car ┆ cam │
│ --- ┆ --- ┆ --- │
│ i64 ┆ i64 ┆ str │
╞═════╪═════╪═════╡
│ 1   ┆ 6   ┆ a   │
│ 2   ┆ 7   ┆ b   │
│ 3   ┆ 8   ┆ c   │
└─────┴─────┴─────┘