polars.first#

polars.first(column: str) Expr[source]#
polars.first(column: Series) Any
polars.first(column: None = None) Expr

Get the first value.

Depending on the input type this function does different things:

input:

  • None -> expression to take first column of a context.

  • str -> syntactic sugar for pl.col(..).first()

  • Series -> Take first value in Series

Examples

>>> df = pl.DataFrame({"a": [1, 8, 3], "b": [4, 5, 2], "c": ["foo", "bar", "foo"]})
>>> df.select(pl.first())
shape: (3, 1)
┌─────┐
│ a   │
│ --- │
│ i64 │
╞═════╡
│ 1   │
├╌╌╌╌╌┤
│ 8   │
├╌╌╌╌╌┤
│ 3   │
└─────┘
>>> df.select(pl.first("a"))
shape: (1, 1)
┌─────┐
│ a   │
│ --- │
│ i64 │
╞═════╡
│ 1   │
└─────┘
>>> pl.first(df["a"])
1