polars.Expr.pow#

Expr.pow(exponent: IntoExprColumn | int | float) → Expr[source]#

Method equivalent of exponentiation operator expr ** exponent.

If the exponent is float, the result follows the dtype of exponent. Otherwise, it follows dtype of base.

Parameters:

exponent: Numeric literal or expression exponent value.

Examples

>>> df = pl.DataFrame({"x": [1, 2, 4, 8]})
>>> df.with_columns(
...     pl.col("x").pow(3).alias("cube"),
...     pl.col("x").pow(pl.col("x").log(2)).alias("x ** xlog2"),
... )
shape: (4, 3)
┌─────┬──────┬────────────┐
│ x   ┆ cube ┆ x ** xlog2 │
│ --- ┆ ---  ┆ ---        │
│ i64 ┆ i64  ┆ f64        │
╞═════╪══════╪════════════╡
│ 1   ┆ 1    ┆ 1.0        │
│ 2   ┆ 8    ┆ 2.0        │
│ 4   ┆ 64   ┆ 16.0       │
│ 8   ┆ 512  ┆ 512.0      │
└─────┴──────┴────────────┘

Raising an integer to a positive integer results in an integer - in order to raise to a negative integer, you can cast either the base or the exponent to float first:

>>> df.with_columns(
...     x_squared=pl.col("x").pow(2),
...     x_inverse=pl.col("x").pow(-1.0),
... )
shape: (4, 3)
┌─────┬───────────┬───────────┐
│ x   ┆ x_squared ┆ x_inverse │
│ --- ┆ ---       ┆ ---       │
│ i64 ┆ i64       ┆ f64       │
╞═════╪═══════════╪═══════════╡
│ 1   ┆ 1         ┆ 1.0       │
│ 2   ┆ 4         ┆ 0.5       │
│ 4   ┆ 16        ┆ 0.25      │
│ 8   ┆ 64        ┆ 0.125     │
└─────┴───────────┴───────────┘