polars.Expr.unique

Expr.unique(
    *,
    maintain_order: bool = False,
) → Expr

Get unique values of this expression.

null is considered to be a unique value for the purposes of this operation.

engine:In MemoryStreamingPartially Distributed

Parameters:

maintain_order

Maintain order of data. This requires more work.

Examples

>>> df = pl.DataFrame({"a": [1, 1, 2]})
>>> df.select(pl.col("a").unique())  
shape: (2, 1)
┌─────┐
│ a   │
│ --- │
│ i64 │
╞═════╡
│ 2   │
│ 1   │
└─────┘
>>> df.select(pl.col("a").unique(maintain_order=True))
shape: (2, 1)
┌─────┐
│ a   │
│ --- │
│ i64 │
╞═════╡
│ 1   │
│ 2   │
└─────┘