polars.LazyFrame.head#

LazyFrame.head(n: int = 5) LDF[source]#

Get the first n rows.

Parameters:
n

Number of rows to return.

Notes

Consider using the fetch() operation if you only want to test your query. The fetch() operation will load the first n rows at the scan level, whereas the head()/limit() are applied at the end.

Examples

>>> df = pl.DataFrame(
...     {
...         "a": [1, 2, 3, 4, 5, 6],
...         "b": [7, 8, 9, 10, 11, 12],
...     }
... ).lazy()
>>> df.head().collect()
shape: (5, 2)
┌─────┬─────┐
│ a   ┆ b   │
│ --- ┆ --- │
│ i64 ┆ i64 │
╞═════╪═════╡
│ 1   ┆ 7   │
├╌╌╌╌╌┼╌╌╌╌╌┤
│ 2   ┆ 8   │
├╌╌╌╌╌┼╌╌╌╌╌┤
│ 3   ┆ 9   │
├╌╌╌╌╌┼╌╌╌╌╌┤
│ 4   ┆ 10  │
├╌╌╌╌╌┼╌╌╌╌╌┤
│ 5   ┆ 11  │
└─────┴─────┘
>>> df.head(2).collect()
shape: (2, 2)
┌─────┬─────┐
│ a   ┆ b   │
│ --- ┆ --- │
│ i64 ┆ i64 │
╞═════╪═════╡
│ 1   ┆ 7   │
├╌╌╌╌╌┼╌╌╌╌╌┤
│ 2   ┆ 8   │
└─────┴─────┘