polars.Expr.is_first_distinct#
- Expr.is_first_distinct() Expr [source]#
Return a boolean mask indicating the first occurrence of each distinct value.
- Returns:
- Expr
Expression of data type
Boolean
.
Examples
>>> df = pl.DataFrame({"a": [1, 1, 2, 3, 2]}) >>> df.with_columns(pl.col("a").is_first_distinct().alias("first")) shape: (5, 2) ┌─────┬───────┐ │ a ┆ first │ │ --- ┆ --- │ │ i64 ┆ bool │ ╞═════╪═══════╡ │ 1 ┆ true │ │ 1 ┆ false │ │ 2 ┆ true │ │ 3 ┆ true │ │ 2 ┆ false │ └─────┴───────┘