polars.arctan2

polars.arctan2(y: str | Expr, x: str | Expr) → Expr

Compute two argument arctan in radians.

Returns the angle (in radians) in the plane between the positive x-axis and the ray from the origin to (x,y).

Parameters:

y

Column name or Expression.

x

Column name or Expression.

Examples

>>> c = (2**0.5) / 2
>>> df = pl.DataFrame(
...     {
...         "y": [c, -c, c, -c],
...         "x": [c, c, -c, -c],
...     }
... )
>>> df.with_columns(pl.arctan2("y", "x").alias("atan2"))
shape: (4, 3)
┌───────────┬───────────┬───────────┐
│ y         ┆ x         ┆ atan2     │
│ ---       ┆ ---       ┆ ---       │
│ f64       ┆ f64       ┆ f64       │
╞═══════════╪═══════════╪═══════════╡
│ 0.707107  ┆ 0.707107  ┆ 0.785398  │
│ -0.707107 ┆ 0.707107  ┆ -0.785398 │
│ 0.707107  ┆ -0.707107 ┆ 2.356194  │
│ -0.707107 ┆ -0.707107 ┆ -2.356194 │
└───────────┴───────────┴───────────┘