polars.Expr.n_unique#
- Expr.n_unique() Expr [source]#
Count unique values.
Notes
null
is considered to be a unique value for the purposes of this operation.Examples
>>> df = pl.DataFrame({"x": [1, 1, 2, 2, 3], "y": [1, 1, 1, None, None]}) >>> df.select( ... x_unique=pl.col("x").n_unique(), ... y_unique=pl.col("y").n_unique(), ... ) shape: (1, 2) ┌──────────┬──────────┐ │ x_unique ┆ y_unique │ │ --- ┆ --- │ │ u32 ┆ u32 │ ╞══════════╪══════════╡ │ 3 ┆ 2 │ └──────────┴──────────┘