polars.Expr.sign

Expr.sign() → Expr

Compute the element-wise sign function on numeric types.

The returned value is computed as follows:

• -1 if x < 0.

• 1 if x > 0.

• x otherwise (typically 0, but could be NaN if the input is).

Null values are preserved as-is, and the dtype of the input is preserved.

Examples

>>> df = pl.DataFrame({"a": [-9.0, -0.0, 0.0, 4.0, float("nan"), None]})
>>> df.select(pl.col.a.sign())
shape: (6, 1)
┌──────┐
│ a    │
│ ---  │
│ f64  │
╞══════╡
│ -1.0 │
│ -0.0 │
│ 0.0  │
│ 1.0  │
│ NaN  │
│ null │
└──────┘