polars.lazyframe.groupby.LazyGroupBy.head

LazyGroupBy.head(n: int = 5) → LazyFrame

Get the first n rows of each group.

Parameters:

n

Number of rows to return.

Examples

>>> df = pl.DataFrame(
...     {
...         "letters": ["c", "c", "a", "c", "a", "b"],
...         "nrs": [1, 2, 3, 4, 5, 6],
...     }
... )
>>> df
shape: (6, 2)
┌─────────┬─────┐
│ letters ┆ nrs │
│ ---     ┆ --- │
│ str     ┆ i64 │
╞═════════╪═════╡
│ c       ┆ 1   │
│ c       ┆ 2   │
│ a       ┆ 3   │
│ c       ┆ 4   │
│ a       ┆ 5   │
│ b       ┆ 6   │
└─────────┴─────┘
>>> df.groupby("letters").head(2).sort("letters")
shape: (5, 2)
┌─────────┬─────┐
│ letters ┆ nrs │
│ ---     ┆ --- │
│ str     ┆ i64 │
╞═════════╪═════╡
│ a       ┆ 3   │
│ a       ┆ 5   │
│ b       ┆ 6   │
│ c       ┆ 1   │
│ c       ┆ 2   │
└─────────┴─────┘